pubmed-mcp-server

Previous value: -"Article identifiers to convert. All IDs must be the same type. DOIs: \"10.1093/nar/gks1195\", PMIDs: \"23193287\", PMCIDs: \"PMC3531190\" (the \"PMC\" prefix is optional — bare digits like \"3531190\" are also accepted)."New value: +"Article identifiers to convert — one identifier per element, all of the same type. Each element is checked against `idType` before the request: `doi` starts with \"10.\" and carries a \"/\" (\"10.1093/nar/gks1195\"); `pmid` is digits (\"23193287\"); `pmcid` is digits with an optional \"PMC\" prefix (\"PMC3531190\" or \"3531190\"). No element may contain a comma or whitespace — a packed value like \"23193287,37952131\" is rejected, so split it across elements."

Previous value: -"Machine-readable failure mode. Declared by this tool: `queue_full`: Local NCBI request queue is at capacity. `ncbi_unreachable`: NCBI E-utilities is unreachable after all retry attempts. `ncbi_deadline_exceeded`: Total request deadline expired before NCBI returned a response. `ncbi_invalid_response`: NCBI returned a body that could not be parsed (invalid XML/JSON). `ncbi_resource_not_found`: NCBI returned a structured \"not found\" error for the requested ID(s). Other values are possible when a failure originates below the handler."New value: +"Machine-readable failure mode. Declared by this tool: `queue_full`: Local NCBI request queue is at capacity. `ncbi_unreachable`: NCBI E-utilities is unreachable after all retry attempts. `ncbi_deadline_exceeded`: Total request deadline expired before NCBI returned a response. `ncbi_invalid_response`: NCBI returned a body that could not be parsed (invalid XML/JSON). `ncbi_resource_not_found`: NCBI returned a structured \"not found\" error for the requested ID(s). `malformed_id`: An `ids` element does not match the declared `idType` — most often several identifiers packed into one element, which the comma-delimited upstream batch would split into extra records. Other values are possible when a failure originates below the handler."

Previous value: -[
-  "queue_full",
-  "ncbi_unreachable",
-  "ncbi_deadline_exceeded",
-  "ncbi_invalid_response",
-  "ncbi_resource_not_found"
-]New value: +[
+  "queue_full",
+  "ncbi_unreachable",
+  "ncbi_deadline_exceeded",
+  "ncbi_invalid_response",
+  "ncbi_resource_not_found",
+  "malformed_id"
+]

Previous value: -"Author list"New value: +"Author list. On a `book-chapter` these are the chapter's own authors, never the book's editors, which are in `book.editors`. Empty on a Bookshelf record that credits neither."

Added value: +{
+  "additionalProperties": false,
+  "description": "The containing book of a `book-chapter`, or the book itself on a `book` record. Present only on those two record types, and never a stand-in for `journalInfo`.",
+  "properties": {
+    "accession": {
+      "description": "NCBI Bookshelf accession from `ArticleIdList` (`bookaccession`), e.g. \"NBK1247\". The record is readable at `https://www.ncbi.nlm.nih.gov/books/<accession>/`.",
+      "type": "string"
+    },
+    "beginningDate": {
+      "description": "First year of a continuously-updated book, from `Book/BeginningDate` (GeneReviews runs from 1993). Absent on a book published once.",
+      "type": "string"
+    },
+    "collectionTitle": {
+      "description": "Series the book belongs to, from `Book/CollectionTitle` (e.g. \"ADA Clinical Compendia Series\"). Absent for a book outside a series.",
+      "type": "string"
+    },
+    "doi": {
+      "description": "The book's own DOI, from `Book/ELocationID` with `EIdType=\"doi\"`. Distinct from the record-level `doi`, which is the chapter's: a chapter does not inherit this one.",
+      "type": "string"
+    },
+    "edition": {
+      "description": "Edition statement from `Book/Edition`. Rare on Bookshelf titles — absent unless NCBI supplies one.",
+      "type": "string"
+    },
+    "editors": {
+      "description": "Editors of the containing book, from `Book/AuthorList` marked `Type=\"editors\"`. Kept out of `authors`, which carries the chapter's own writers. Absent when the book credits no editors.",
+      "items": {
+        "additionalProperties": false,
+        "description": "One editor of the containing book. Name parts only — editors are a citation credit, not a contributor record, so no affiliations or ORCID are reported for them.",
+        "properties": {
+          "collectiveName": {
+            "description": "Group or committee credited as editor, when the entry names an organization rather than a person. Mutually exclusive with the name-part fields.",
+            "type": "string"
+          },
+          "firstName": {
+            "description": "Editor given name as NCBI supplies it (`ForeName`, often \"Margaret P\"). Absent when NCBI carries initials only, or on a group editor.",
+            "type": "string"
+          },
+          "initials": {
+            "description": "Editor initials with no separators (e.g. \"MP\"). Absent when NCBI supplies none, or on a group editor.",
+            "type": "string"
+          },
+          "lastName": {
+            "description": "Editor surname, from the book's `Book/AuthorList Type=\"editors\"` entry. Absent on a group editor, which carries `collectiveName` instead.",
+            "type": "string"
+          }
+        },
+        "type": "object"
+      },
+      "type": "array"
+    },
+    "endingDate": {
+      "description": "Last year of a closed date range, from `Book/EndingDate`. Absent while a book is still being updated, which leaves the range open-ended.",
+      "type": "string"
+    },
+    "isbns": {
+      "description": "Every `Book/Isbn` on the record. A book commonly carries a print and an electronic ISBN, so this is a list. Absent for a Bookshelf title with no ISBN, which is most of them.",
+      "items": {
+        "description": "One ISBN, verbatim as NCBI reports it — leading zeros intact",
+        "type": "string"
+      },
+      "type": "array"
+    },
+    "medium": {
+      "description": "Medium the book is published in, from `Book/Medium` — \"Internet\" wherever NCBI supplies it. Absent when NCBI supplies none; it is never defaulted.",
+      "type": "string"
+    },
+    "pubDate": {
+      "description": "Publication year from `Book/PubDate`. Year only — NCBI's month and day are not reported, since no citation style uses them for a book.",
+      "type": "string"
+    },
+    "publisher": {
+      "description": "Publisher of the book, from `Book/Publisher/PublisherName`.",
+      "type": "string"
+    },
+    "publisherLocation": {
+      "description": "Place of publication, from `Book/Publisher/PublisherLocation` (e.g. \"Seattle (WA)\"). Absent when NCBI supplies no place.",
+      "type": "string"
+    },
+    "title": {
+      "description": "Title of the containing book, from `Book/BookTitle` (e.g. \"GeneReviews®\"). On a `book` record this is the same value as the record's own `title`.",
+      "type": "string"
+    }
+  },
+  "type": "object"
+}

Previous value: -"Journal information"New value: +"Journal information. Present on `journal-article` records only — absent on `book-chapter` and `book` records, because a Bookshelf record has no journal and its book title is never reported as one; read `book` for those. (#114)"

Added value: +{
+  "description": "Electronic article locator from NCBI `ELocationID` — the publisher-assigned article number (e.g. \"2400512\"). Journals that assign article numbers instead of pages often omit pagination entirely, leaving this the only locator. Never a substitute for `pages`, and never the DOI: a DOI-typed `ELocationID` is reported in `doi` instead. Absent when the only locator NCBI supplies is marked invalid.",
+  "type": "string"
+}

Added value: +{
+  "description": "Type of `elocationId`, from NCBI's `EIdType` attribute — \"pii\" in practice. Free-form: NCBI does not close the set, so treat an unfamiliar value as opaque.",
+  "type": "string"
+}

Added value: +{
+  "description": "Which kind of PubMed record this is, set from the XML element it arrived in: `journal-article` for an ordinary article, `book-chapter` for an NCBI Bookshelf chapter, `book` for a whole Bookshelf book. Read this to tell the three apart — `publicationTypes` cannot, because PubMed labels a Bookshelf record \"Review\" or \"Study Guide\". `journalInfo` is present only on `journal-article`; `book` only on the other two.",
+  "enum": [
+    "journal-article",
+    "book-chapter",
+    "book"
+  ],
+  "type": "string"
+}

Previous value: -"Article title"New value: +"Article title — the chapter title on a `book-chapter`, and the book title on a `book` record, where it repeats `book.title`."

Added value: +[
+  "recordType"
+]

Previous value: -"PMIDs that returned no article data. Reported in full regardless of where a `maxResponseCharacters` cutoff lands — these are misses, not deferrals, and re-requesting them returns nothing."New value: +"PMIDs PubMed returned no record for. That is all this reports: PubMed omits an unknown PMID silently, with no error and no reason, so the absence says nothing about whether the PMID exists. Reported in full regardless of where a `maxResponseCharacters` cutoff lands — these are misses, not deferrals. Use `pubmed_search_articles` to find PMIDs that do resolve."

Previous value: -"DOIs to resolve (e.g. [\"10.21203/rs.3.rs-9010375/v1\"]). Provide exactly one of `pmcids`, `pmids`, or `dois`. Resolved to a PMCID via the PMC ID Converter and returned as structured JATS when the article is in PMC; DOIs with no PMC counterpart (preprints, EPMC-only OA) fall through to Europe PMC, then Unpaywall, when those layers are enabled."New value: +"DOIs to resolve (e.g. [\"10.21203/rs.3.rs-9010375/v1\"]), one per element. Provide exactly one of `pmcids`, `pmids`, or `dois`. Resolved to a PMCID via the PMC ID Converter and returned as structured JATS when the article is in PMC; DOIs with no PMC counterpart (preprints, EPMC-only OA) fall through to Europe PMC, then Unpaywall, when those layers are enabled."

Removed value: -3

Added value: +"^10\\.[^\\s,]+\\/[^\\s,]+$"

Added value: +{
+  "default": true,
+  "description": "Include the article's figures and supplementary material — `assets[]`, each with its label, caption, enclosing section and deposit pointer. On by default because it is cheaper than tables: a median asset-bearing article grows about 10%, and the body prose already refers to these by label. Set false to omit them, which also removes the `[Figure: …]` / `[Supplementary: …]` markers from the section text, since without the array they point at nothing. Prose-shaped blocks — lists, definition lists, block quotes, boxed text, preformatted blocks, displayed formulae — are section text rather than assets and this switch never affects them. Applies to `source=pmc` results only.",
+  "type": "boolean"
+}

Added value: +{
+  "default": true,
+  "description": "Include the article's tables — cells, captions, labels and footnotes. On by default because a dropped table takes its numbers with it. Table-dense articles pay for it: rendered tables typically add 12–17% to an article record and can more than double it. Set false to omit them, or cap the cost with `maxCharacters`, which drops tables it cannot fit whole. Applies to `source=pmc` results only.",
+  "type": "boolean"
+}

Previous value: -"Per-article budget for body text, in characters. Counts `source=pmc` section and subsection text, or the `source=unpaywall` `content` body; titles, abstracts, identifiers, and references are never counted or shortened. Applied after `sections`, `maxSections`, and `includeReferences`, so semantic filtering is unaffected. This knob alone bounds only bodies: the response-wide ceiling it implies is this value times the number of articles returned, plus every uncounted field. Use `maxResponseCharacters` for a true whole-response ceiling. Omit for the full body."New value: +"Per-article budget for body text, in characters. Counts `source=pmc` section and subsection text — which carries the inline blocks the parser renders in place, such as lists, definition lists, block quotes, boxed text, preformatted blocks and displayed formulae — plus table label, caption, cell and footnote text and asset label, caption and `href` text; or the `source=unpaywall` `content` body. Titles, abstracts, identifiers, and references are never counted or shortened. The counted unit is that text alone — the Markdown grid `content[]` renders around the cells (pipes, padding, the divider row, headings) is scaffolding this budget does not measure, so a table renders longer than it costs here. Sections are served first, then tables, then assets, each spending what is left, in document order — admission stops at the first entry that does not fit, and every entry from there on is dropped whole rather than cut mid-row or returned with a shortened caption, counted in `truncation.omittedTables` / `truncation.omittedAssets` and named in `truncation.articles[].omittedTableNames` / `omittedAssetNames`. Applied after `sections`, `maxSections`, `includeReferences`, `includeTables`, and `includeAssets`, so semantic filtering is unaffected. This knob alone bounds only bodies: the response-wide ceiling it implies is this value times the number of articles returned, plus every uncounted field. Use `maxResponseCharacters` for a true whole-response ceiling. Omit for the full body."

Previous value: -"Filter to specific sections by title, case-insensitive (e.g. [\"Introduction\", \"Methods\", \"Results\", \"Discussion\"]). Applies to `source=pmc` results only."New value: +"Filter to specific sections by title (e.g. [\"Introduction\", \"Methods\", \"Results\", \"Discussion\"]). A term matches a section or subsection title at any nesting depth, case-insensitively, as a substring — \"resul\" matches \"Results\". A section whose own title matches is returned whole; one kept only because a nested subsection matched keeps its heading as a breadcrumb, with its own text cleared and only the matching branch beneath it. Tables and assets narrow with the filter: one whose section did not survive, or that names no section, is dropped. Applies to `source=pmc` results only."

Previous value: -[
-  {
-    "additionalProperties": false,
-    "description": "Structured JATS full-text article. `viaSource` records whether the JATS came from NCBI PMC or Europe PMC.",
-    "properties": {
-      "abstract": {
-        "description": "Abstract",
-        "type": "string"
-      },
-      "affiliations": {
-        "description": "Author affiliations",
-        "items": {
-          "type": "string"
-        },
-        "type": "array"
-      },
-      "articleType": {
-        "description": "Article type",
-        "type": "string"
-      },
-      "authors": {
-        "description": "Authors",
-        "items": {
-          "additionalProperties": false,
-          "description": "Author entry",
-          "properties": {
-            "collectiveName": {
-              "description": "Group name",
-              "type": "string"
-            },
-            "givenNames": {
-              "description": "Given names",
-              "type": "string"
-            },
-            "lastName": {
-              "description": "Last name",
-              "type": "string"
-            }
-          },
-          "type": "object"
-        },
-        "type": "array"
-      },
-      "doi": {
-        "description": "DOI, cased as the tier that served this record reports it (NCBI PMC, Europe PMC, or Unpaywall). DOIs are case-insensitive by spec and no case normalization is applied here, so casing can differ between tiers and from other tools — compare case-insensitively.",
-        "type": "string"
-      },
-      "epmcId": {
-        "description": "Europe PMC record id — present when `viaSource` is `europepmc`",
-        "type": "string"
-      },
-      "epmcSource": {
-        "description": "Europe PMC source code when `viaSource` is `europepmc`. Common values: `MED` (PubMed-derived), `PMC` (PMC counterpart), `PPR` (preprint), `PAT` (patent), `AGR` (Agricola), plus less common codes (`CTX`, `CBA`, `ETH`, `HIR`). Treat as opaque — EPMC may introduce new codes.",
-        "type": "string"
-      },
-      "journal": {
-        "additionalProperties": false,
-        "description": "Journal information",
-        "properties": {
-          "issn": {
-            "description": "ISSN",
-            "type": "string"
-          },
-          "issue": {
-            "description": "Issue number",
-            "type": "string"
-          },
-          "pages": {
-            "description": "Page range",
-            "type": "string"
-          },
-          "title": {
-            "description": "Journal title",
-            "type": "string"
-          },
-          "volume": {
-            "description": "Volume number",
-            "type": "string"
-          }
-        },
-        "type": "object"
-      },
-      "keywords": {
-        "description": "Keywords",
-        "items": {
-          "type": "string"
-        },
-        "type": "array"
-      },
-      "pmcId": {
-        "description": "PMC ID — present for NCBI PMC records and Europe PMC entries that have a PMC counterpart. Absent for EPMC-only records like preprints; use `epmcId` in that case.",
-        "type": "string"
-      },
-      "pmcUrl": {
-        "description": "PMC URL — derived from `pmcId` when present",
-        "type": "string"
-      },
-      "pmid": {
-        "description": "PubMed ID",
-        "type": "string"
-      },
-      "publicationDate": {
-        "additionalProperties": false,
-        "description": "Publication date",
-        "properties": {
-          "day": {
-            "description": "Publication day",
-            "type": "string"
-          },
-          "month": {
-            "description": "Publication month",
-            "type": "string"
-          },
-          "year": {
-            "description": "Publication year",
-            "type": "string"
-          }
-        },
-        "type": "object"
-      },
-      "pubmedUrl": {
-        "description": "PubMed URL",
-        "type": "string"
-      },
-      "references": {
-        "description": "Reference list",
-        "items": {
-          "additionalProperties": false,
-          "description": "Reference entry",
-          "properties": {
-            "citation": {
-              "description": "Citation text",
-              "type": "string"
-            },
-            "id": {
-              "description": "Reference ID",
-              "type": "string"
-            },
-            "label": {
-              "description": "Reference label",
-              "type": "string"
-            }
-          },
-          "required": [
-            "citation"
-          ],
-          "type": "object"
-        },
-        "type": "array"
-      },
-      "sections": {
-        "description": "Article body sections",
-        "items": {
-          "additionalProperties": false,
-          "description": "Article body section",
-          "properties": {
-            "label": {
-              "description": "Section label",
-              "type": "string"
-            },
-            "subsections": {
-              "description": "Nested subsections",
-              "items": {
-                "additionalProperties": false,
-                "description": "Article subsection",
-                "properties": {
-                  "label": {
-                    "description": "Subsection label",
-                    "type": "string"
-                  },
-                  "text": {
-                    "description": "Subsection body text. Sections nested deeper than this level are folded in here in document order, each heading rendered on its own line above its text.",
-                    "type": "string"
-                  },
-                  "title": {
-                    "description": "Subsection heading",
-                    "type": "string"
-                  }
-                },
-                "required": [
-                  "text"
-                ],
-                "type": "object"
-              },
-              "type": "array"
-            },
-            "text": {
-              "description": "Section body text",
-              "type": "string"
-            },
-            "title": {
-              "description": "Section heading",
-              "type": "string"
-            }
-          },
-          "required": [
-            "text"
-          ],
-          "type": "object"
-        },
-        "type": "array"
-      },
-      "source": {
-        "const": "pmc",
-        "description": "Structured JATS — same DTD whether sourced from NCBI PMC or Europe PMC",
-        "type": "string"
-      },
-      "title": {
-        "description": "Article title",
-        "type": "string"
-      },
-      "viaSource": {
-        "description": "Which layer produced the JATS: `pmc` for NCBI PMC EFetch (db=pmc), `europepmc` for Europe PMC `fullTextXML`. Both paths return the same JATS shape; the discriminator records origin for observability and license attribution.",
-        "enum": [
-          "pmc",
-          "europepmc"
-        ],
-        "type": "string"
-      }
-    },
-    "required": [
-      "source",
-      "viaSource",
-      "sections"
-    ],
-    "type": "object"
-  },
-  {
-    "additionalProperties": false,
-    "description": "Best-effort full text from an open-access copy",
-    "properties": {
-      "content": {
-        "description": "Full article text — Markdown or plain text per `contentFormat`",
-        "type": "string"
-      },
-      "contentFormat": {
-        "description": "How `content` was extracted. html-markdown: Defuddle extracted Markdown from an HTML landing page; light section structure may survive but is not guaranteed. pdf-text: unpdf extracted plain text from a PDF; no section, reference, or heading structure.",
-        "enum": [
-          "html-markdown",
-          "pdf-text"
-        ],
-        "type": "string"
-      },
-      "doi": {
-        "description": "DOI used to locate the open-access copy",
-        "type": "string"
-      },
-      "hostType": {
-        "description": "`publisher` or `repository` — where the OA copy is hosted",
-        "type": "string"
-      },
-      "license": {
-        "description": "License identifier from Unpaywall (e.g. cc-by, cc0)",
-        "type": "string"
-      },
-      "pmcId": {
-        "description": "PMC ID this article was requested under, in `PMC<digits>` form — present for `pmcids` input, absent for `pmids` and `dois` input. Ties the article back to the requested identifier, which `unavailable[]` keys on for the ids that found nothing.",
-        "type": "string"
-      },
-      "pmid": {
-        "description": "PubMed ID when input was `pmids`; absent for `pmcids` and `dois` input",
-        "type": "string"
-      },
-      "pubmedUrl": {
-        "description": "PubMed URL — present when `pmid` is set",
-        "type": "string"
-      },
-      "source": {
-        "const": "unpaywall",
-        "description": "Content fetched from an open-access copy indexed by Unpaywall. Best-effort — structural fidelity depends on `contentFormat`.",
-        "type": "string"
-      },
-      "sourceUrl": {
-        "description": "URL the content was fetched from",
-        "type": "string"
-      },
-      "title": {
-        "description": "Detected article title when present",
-        "type": "string"
-      },
-      "totalPages": {
-        "description": "Page count reported by the PDF extractor; absent for HTML",
-        "type": "number"
-      },
-      "version": {
-        "description": "OA version: submittedVersion | acceptedVersion | publishedVersion",
-        "type": "string"
-      },
-      "viaSource": {
-        "const": "unpaywall",
-        "description": "Layer that produced this article. Constant `unpaywall` for this branch.",
-        "type": "string"
-      },
-      "wordCount": {
-        "description": "Approximate word count reported by the HTML extractor; absent for PDFs",
-        "type": "number"
-      }
-    },
-    "required": [
-      "source",
-      "viaSource",
-      "contentFormat",
-      "doi",
-      "sourceUrl",
-      "content"
-    ],
-    "type": "object"
-  }
-]New value: +[
+  {
+    "additionalProperties": false,
+    "description": "Structured JATS full-text article. `viaSource` records whether the JATS came from NCBI PMC or Europe PMC.",
+    "properties": {
+      "abstract": {
+        "description": "Abstract",
+        "type": "string"
+      },
+      "affiliations": {
+        "description": "Author affiliations",
+        "items": {
+          "type": "string"
+        },
+        "type": "array"
+      },
+      "articleType": {
+        "description": "Article type",
+        "type": "string"
+      },
+      "assets": {
+        "description": "Every `<fig>` and `<supplementary-material>` the article carries, in document order — from the body and from `<floats-group>`, `<back>` and appendices alike. Each one lifted from the body leaves a `[Figure: <label>]` or `[Supplementary: <label>]` marker at its position in the section text, so reading order survives the lift. Absent when the article deposits none, when `includeAssets` is false, or when a `sections` filter left none standing.",
+        "items": {
+          "additionalProperties": false,
+          "description": "One figure or supplementary-material item, with its caption, pointer, and section",
+          "properties": {
+            "assetType": {
+              "description": "Which captioned element this came from — `figure` for a `<fig>`, `supplementary-material` for a `<supplementary-material>` deposit",
+              "enum": [
+                "figure",
+                "supplementary-material"
+              ],
+              "type": "string"
+            },
+            "caption": {
+              "description": "Caption text, with the label excluded",
+              "type": "string"
+            },
+            "href": {
+              "description": "The `<graphic>`/`<media>` `@xlink:href` exactly as deposited — a pointer into the PMC deposit (`MOL2-20-1253-g001.jpg`), not a fetchable URL. No absolute form of it resolves; read the rendered article at `pmcUrl` instead. Absent when the deposit names no file.",
+              "type": "string"
+            },
+            "id": {
+              "description": "JATS `id` attribute — the target body-text cross-references point at",
+              "type": "string"
+            },
+            "label": {
+              "description": "Display label as printed, e.g. `Fig. 1`",
+              "type": "string"
+            },
+            "sectionTitle": {
+              "description": "Title of the innermost section enclosing the asset, wherever that section sits — body, `<back>` matter, or an appendix all count. Absent for an asset inside no section at all, such as a `<floats-group>` deposit.",
+              "type": "string"
+            }
+          },
+          "required": [
+            "assetType"
+          ],
+          "type": "object"
+        },
+        "type": "array"
+      },
+      "authors": {
+        "description": "Authors",
+        "items": {
+          "additionalProperties": false,
+          "description": "Author entry",
+          "properties": {
+            "collectiveName": {
+              "description": "Group name",
+              "type": "string"
+            },
+            "givenNames": {
+              "description": "Given names",
+              "type": "string"
+            },
+            "lastName": {
+              "description": "Last name",
+              "type": "string"
+            }
+          },
+          "type": "object"
+        },
+        "type": "array"
+      },
+      "doi": {
+        "description": "DOI, cased as the tier that served this record reports it (NCBI PMC, Europe PMC, or Unpaywall). DOIs are case-insensitive by spec and no case normalization is applied here, so casing can differ between tiers and from other tools — compare case-insensitively.",
+        "type": "string"
+      },
+      "epmcId": {
+        "description": "Europe PMC record id — present when `viaSource` is `europepmc`",
+        "type": "string"
+      },
+      "epmcSource": {
+        "description": "Europe PMC source code when `viaSource` is `europepmc`. Common values: `MED` (PubMed-derived), `PMC` (PMC counterpart), `PPR` (preprint), `PAT` (patent), `AGR` (Agricola), plus less common codes (`CTX`, `CBA`, `ETH`, `HIR`). Treat as opaque — EPMC may introduce new codes.",
+        "type": "string"
+      },
+      "journal": {
+        "additionalProperties": false,
+        "description": "Journal information",
+        "properties": {
+          "elocationId": {
+            "description": "Electronic article locator from JATS `<elocation-id>` — the publisher-assigned article number (e.g. \"e20542\"). Journals that assign article numbers deposit no `<fpage>`, so this is the only locator on roughly half of PMC records. Never a substitute for `pages`; JATS carries no type attribute, so there is no counterpart to the `elocationIdType` that `pubmed_fetch_articles` reports.",
+            "type": "string"
+          },
+          "issn": {
+            "description": "ISSN",
+            "type": "string"
+          },
+          "issue": {
+            "description": "Issue number",
+            "type": "string"
+          },
+          "pages": {
+            "description": "Page range",
+            "type": "string"
+          },
+          "title": {
+            "description": "Journal title",
+            "type": "string"
+          },
+          "volume": {
+            "description": "Volume number",
+            "type": "string"
+          }
+        },
+        "type": "object"
+      },
+      "keywords": {
+        "description": "Keywords",
+        "items": {
+          "type": "string"
+        },
+        "type": "array"
+      },
+      "pmcId": {
+        "description": "PMC ID — present for NCBI PMC records and Europe PMC entries that have a PMC counterpart. Absent for EPMC-only records like preprints; use `epmcId` in that case.",
+        "type": "string"
+      },
+      "pmcUrl": {
+        "description": "PMC URL — derived from `pmcId` when present",
+        "type": "string"
+      },
+      "pmid": {
+        "description": "PubMed ID",
+        "type": "string"
+      },
+      "publicationDate": {
+        "additionalProperties": false,
+        "description": "Publication date",
+        "properties": {
+          "day": {
+            "description": "Publication day",
+            "type": "string"
+          },
+          "month": {
+            "description": "Publication month",
+            "type": "string"
+          },
+          "year": {
+            "description": "Publication year",
+            "type": "string"
+          }
+        },
+        "type": "object"
+      },
+      "pubmedUrl": {
+        "description": "PubMed URL",
+        "type": "string"
+      },
+      "references": {
+        "description": "Reference list",
+        "items": {
+          "additionalProperties": false,
+          "description": "Reference entry",
+          "properties": {
+            "citation": {
+              "description": "Citation text",
+              "type": "string"
+            },
+            "id": {
+              "description": "Reference ID",
+              "type": "string"
+            },
+            "label": {
+              "description": "Reference label",
+              "type": "string"
+            }
+          },
+          "required": [
+            "citation"
+          ],
+          "type": "object"
+        },
+        "type": "array"
+      },
+      "sections": {
+        "description": "Article body sections",
+        "items": {
+          "additionalProperties": false,
+          "description": "Article body section",
+          "properties": {
+            "label": {
+              "description": "Section label",
+              "type": "string"
+            },
+            "subsections": {
+              "description": "Nested subsections",
+              "items": {
+                "additionalProperties": false,
+                "description": "Article subsection",
+                "properties": {
+                  "label": {
+                    "description": "Subsection label",
+                    "type": "string"
+                  },
+                  "text": {
+                    "description": "Subsection body text. Sections nested deeper than this level are folded in here in document order, each heading rendered on its own line above its text.",
+                    "type": "string"
+                  },
+                  "title": {
+                    "description": "Subsection heading",
+                    "type": "string"
+                  }
+                },
+                "required": [
+                  "text"
+                ],
+                "type": "object"
+              },
+              "type": "array"
+            },
+            "text": {
+              "description": "Section body text",
+              "type": "string"
+            },
+            "title": {
+              "description": "Section heading",
+              "type": "string"
+            }
+          },
+          "required": [
+            "text"
+          ],
+          "type": "object"
+        },
+        "type": "array"
+      },
+      "source": {
+        "const": "pmc",
+        "description": "Structured JATS — same DTD whether sourced from NCBI PMC or Europe PMC",
+        "type": "string"
+      },
+      "tables": {
+        "description": "Every `<table-wrap>` the article carries, in document order — from the body and from `<floats-group>`, `<back>` and appendices alike. Absent when the article deposits none, when `includeTables` is false, or when a `sections` filter left none standing.",
+        "items": {
+          "additionalProperties": false,
+          "description": "One table from the article, with its cells, caption, and owning section",
+          "properties": {
+            "caption": {
+              "description": "Caption text, with the label excluded",
+              "type": "string"
+            },
+            "footnotes": {
+              "description": "`<table-wrap-foot>` text, flattened to one string",
+              "type": "string"
+            },
+            "headerRowCount": {
+              "description": "How many leading `rows` entries are header rows — a `<thead>` block, or leading rows made entirely of `<th>`. 0 when the table declares none. Several header rows stack: read one column top to bottom for its full header path.",
+              "type": "number"
+            },
+            "id": {
+              "description": "JATS `id` attribute — the target body-text cross-references point at",
+              "type": "string"
+            },
+            "label": {
+              "description": "Table label as printed, e.g. `TABLE 1`",
+              "type": "string"
+            },
+            "rows": {
+              "description": "Cell text by row, in document order, one entry per grid column. `colspan` and `rowspan` are expanded, so a cell covering several columns or rows repeats its text across each cell it covers and a well-formed table is rectangular — align on position from the left, and read a repeated value as one spanning cell rather than several measurements. Empty when `unextractableReason` is set.",
+              "items": {
+                "description": "One row, as cell text by grid column",
+                "items": {
+                  "type": "string"
+                },
+                "type": "array"
+              },
+              "type": "array"
+            },
+            "sectionTitle": {
+              "description": "Title of the innermost section enclosing the table, wherever that section sits — body, `<back>` matter, or an appendix all count, and in back matter the section name is the only positional cue there is. Absent only for a table inside no section at all, such as a `<floats-group>` deposit.",
+              "type": "string"
+            },
+            "unextractableReason": {
+              "description": "Why `rows` is empty — set only then. graphic-only: the table was deposited as an image with no underlying markup. cals-tgroup: the table uses the CALS `<tgroup>` model, which this server does not extract (0 of 283 tables in an open-access survey used it). no-rows: the markup carried no rows. The label and caption are still returned, so a table that could not be read is visible rather than silently missing.",
+              "enum": [
+                "cals-tgroup",
+                "graphic-only",
+                "no-rows"
+              ],
+              "type": "string"
+            }
+          },
+          "required": [
+            "headerRowCount",
+            "rows"
+          ],
+          "type": "object"
+        },
+        "type": "array"
+      },
+      "title": {
+        "description": "Article title",
+        "type": "string"
+      },
+      "viaSource": {
+        "description": "Which layer produced the JATS: `pmc` for NCBI PMC EFetch (db=pmc), `europepmc` for Europe PMC `fullTextXML`. Both paths return the same JATS shape; the discriminator records origin for observability and license attribution.",
+        "enum": [
+          "pmc",
+          "europepmc"
+        ],
+        "type": "string"
+      }
+    },
+    "required": [
+      "source",
+      "viaSource",
+      "sections"
+    ],
+    "type": "object"
+  },
+  {
+    "additionalProperties": false,
+    "description": "Best-effort full text from an open-access copy",
+    "properties": {
+      "content": {
+        "description": "Full article text — Markdown or plain text per `contentFormat`",
+        "type": "string"
+      },
+      "contentFormat": {
+        "description": "How `content` was extracted. html-markdown: Defuddle extracted Markdown from an HTML landing page; light section structure may survive but is not guaranteed. pdf-text: unpdf extracted plain text from a PDF; no section, reference, or heading structure.",
+        "enum": [
+          "html-markdown",
+          "pdf-text"
+        ],
+        "type": "string"
+      },
+      "doi": {
+        "description": "DOI used to locate the open-access copy",
+        "type": "string"
+      },
+      "hostType": {
+        "description": "`publisher` or `repository` — where the OA copy is hosted",
+        "type": "string"
+      },
+      "license": {
+        "description": "License identifier from Unpaywall (e.g. cc-by, cc0)",
+        "type": "string"
+      },
+      "pmcId": {
+        "description": "PMC ID this article was requested under, in `PMC<digits>` form — present for `pmcids` input, absent for `pmids` and `dois` input. Ties the article back to the requested identifier, which `unavailable[]` keys on for the ids that found nothing.",
+        "type": "string"
+      },
+      "pmid": {
+        "description": "PubMed ID when input was `pmids`; absent for `pmcids` and `dois` input",
+        "type": "string"
+      },
+      "pubmedUrl": {
+        "description": "PubMed URL — present when `pmid` is set",
+        "type": "string"
+      },
+      "source": {
+        "const": "unpaywall",
+        "description": "Content fetched from an open-access copy indexed by Unpaywall. Best-effort — structural fidelity depends on `contentFormat`.",
+        "type": "string"
+      },
+      "sourceUrl": {
+        "description": "URL the content was fetched from",
+        "type": "string"
+      },
+      "title": {
+        "description": "Detected article title when present",
+        "type": "string"
+      },
+      "totalPages": {
+        "description": "Page count reported by the PDF extractor; absent for HTML",
+        "type": "number"
+      },
+      "version": {
+        "description": "OA version: submittedVersion | acceptedVersion | publishedVersion",
+        "type": "string"
+      },
+      "viaSource": {
+        "const": "unpaywall",
+        "description": "Layer that produced this article. Constant `unpaywall` for this branch.",
+        "type": "string"
+      },
+      "wordCount": {
+        "description": "Approximate word count reported by the HTML extractor; absent for PDFs",
+        "type": "number"
+      }
+    },
+    "required": [
+      "source",
+      "viaSource",
+      "contentFormat",
+      "doi",
+      "sourceUrl",
+      "content"
+    ],
+    "type": "object"
+  }
+]

Previous value: -"Optional guidance for a partial or empty body. A `sections`-filter miss names the requested terms and affected article id(s) and suggests retrying without `sections` or using broader headings. A metadata-only record names the id(s) the chain could retrieve as front matter only and points at `pubmed_fetch_articles` for the abstract. A budgeted response names the characters returned versus carried and points at `truncation`. A response-wide budget that deferred articles names the ids to re-request. Absent when none of those applies."New value: +"Optional guidance for a partial or empty body. A `sections`-filter miss names the requested terms and affected article id(s) and suggests retrying without `sections` or using broader headings. A metadata-only record names the id(s) the chain could retrieve as front matter only and points at `pubmed_fetch_articles` for the abstract. A table returned with no cell values names the affected table(s), the article each came from, and why the cells cannot be recovered. A budgeted response names the characters returned versus carried and points at `truncation`. A response-wide budget that deferred articles names the ids to re-request. Absent when none of those applies."

Added value: +{
+  "description": "The dropped assets by name, in document order — each asset's label, else its `id`, else `asset <n>` for its position in the article. Contiguous for the same reason `omittedTableNames` is: admission stops at the first asset that did not fit rather than skipping ahead to a smaller one. Absent when none were dropped.",
+  "items": {
+    "type": "string"
+  },
+  "type": "array"
+}

Added value: +{
+  "description": "Figures and supplementary items this article dropped whole because the budget left no room once sections and tables were served. An asset is never returned with a truncated caption, so it is either returned complete or counted here. Absent when none were dropped.",
+  "type": "number"
+}

Added value: +{
+  "description": "The dropped tables by name, in document order — each table's label, else its `id`, else `table <n>` for its position in the article. Names the tables a bare count only hints at, the way `deferred.ids` names deferred articles. Every table from the first that did not fit onward is here: admission stops at that table rather than skipping ahead to a smaller one, so these are contiguous. Absent when none were dropped.",
+  "items": {
+    "type": "string"
+  },
+  "type": "array"
+}

Added value: +{
+  "description": "Tables this article dropped whole because the budget left no room for them. A table is never cut mid-row, so it is either returned complete or counted here. Absent when none were dropped.",
+  "type": "number"
+}

Added value: +{
+  "description": "Figures and supplementary items dropped whole across every budgeted article, because the budget left no room once body sections and tables were served. Absent when none were dropped. Re-request the affected articles with a higher `maxCharacters`, or with `sections` narrowed, to receive them.",
+  "type": "number"
+}

Added value: +{
+  "description": "Tables dropped whole across every budgeted article, because the budget left no room once body sections were served. Absent when none were dropped. Re-request the affected articles with a higher `maxCharacters`, or with `sections` narrowed, to receive them.",
+  "type": "number"
+}

Previous value: -"Why no full text was returned — the most specific signal any tier that answered reported. not-found: upstream returned no record for this ID. no-pmc-fallback-disabled: every tier was skipped (`triedTiers` is all `not-attempted`) — typically because EPMC (`EUROPEPMC_ENABLED`) and Unpaywall (`UNPAYWALL_EMAIL`) are not configured. no-epmc-fulltext: EPMC indexed the record but publishes no fullTextXML. no-body: the record was retrieved but carries front matter and abstract only, with no body sections — use `pubmed_fetch_articles` for the metadata. no-doi: no DOI to query Unpaywall. no-oa: Unpaywall has no OA copy. fetch-failed: download failed. parse-failed: extraction empty. service-error: upstream server failure (threw, timed out, or returned malformed data). A reason never means the chain ran to completion — read `unqueriedTiers` for that."New value: +"Why no full text was returned — the most specific signal any tier that answered reported. not-found: upstream returned no record for this ID. no-pmc-fallback-disabled: every tier was skipped (`triedTiers` is all `not-attempted`) — typically because EPMC (`EUROPEPMC_ENABLED`) and Unpaywall (`UNPAYWALL_EMAIL`) are not configured. no-epmc-fulltext: EPMC indexed the record but publishes no fullTextXML. no-body: the record was retrieved but carries front matter and abstract only, with no body sections — use `pubmed_fetch_articles` for the metadata. no-doi: the DOI lookup ran and this record has none, so Unpaywall could not be queried. doi-lookup-failed: the DOI lookup itself errored, so whether a DOI exists is unknown and Unpaywall was never reached — retry the request; unlike no-doi this is a transient failure, not a settled answer. no-oa: Unpaywall has no OA copy. fetch-failed: download failed. parse-failed: extraction empty. service-error: upstream server failure (threw, timed out, or returned malformed data). A reason never means the chain ran to completion — read `unqueriedTiers` for that."

Previous value: -[
-  "not-found",
-  "no-pmc-fallback-disabled",
-  "no-epmc-fulltext",
-  "no-body",
-  "no-doi",
-  "no-oa",
-  "fetch-failed",
-  "parse-failed",
-  "service-error"
-]New value: +[
+  "not-found",
+  "no-pmc-fallback-disabled",
+  "no-epmc-fulltext",
+  "no-body",
+  "no-doi",
+  "doi-lookup-failed",
+  "no-oa",
+  "fetch-failed",
+  "parse-failed",
+  "service-error"
+]

Previous value: -"Per-tier outcome. not-attempted: tier was skipped. miss: tier returned no record. no-fulltext: EPMC indexed the record but publishes no fullTextXML. no-body: the tier returned a record with front matter and abstract but no body sections, so the chain continued. no-doi: no DOI to query Unpaywall. no-oa: Unpaywall reports no open-access copy. fetch-failed: OA copy download failed. parse-failed: extraction produced empty content. service-error: tier service threw."New value: +"Per-tier outcome. not-attempted: tier was skipped. miss: tier returned no record. no-fulltext: EPMC indexed the record but publishes no fullTextXML. no-body: the tier returned a record with front matter and abstract but no body sections, so the chain continued. no-doi: the DOI lookup ran and this record has none, so Unpaywall could not be queried. doi-lookup-failed: the DOI lookup itself errored, so whether a DOI exists is unknown and Unpaywall was never reached — retry the request. no-oa: Unpaywall reports no open-access copy. fetch-failed: OA copy download failed. parse-failed: extraction produced empty content. service-error: tier service threw."

Previous value: -[
-  "not-attempted",
-  "miss",
-  "no-fulltext",
-  "no-body",
-  "no-doi",
-  "no-oa",
-  "fetch-failed",
-  "parse-failed",
-  "service-error"
-]New value: +[
+  "not-attempted",
+  "miss",
+  "no-fulltext",
+  "no-body",
+  "no-doi",
+  "doi-lookup-failed",
+  "no-oa",
+  "fetch-failed",
+  "parse-failed",
+  "service-error"
+]

Previous value: -"Author string"New value: +"Author string — the first three of the record's own authors, then \"et al.\". On an NCBI Bookshelf chapter these are the chapter's authors; the book's editors are in `editors`."

Added value: +{
+  "description": "Title of the book an NCBI Bookshelf record belongs to. Present instead of `source` on a book record; absent on a journal article.",
+  "type": "string"
+}

Added value: +{
+  "description": "What PubMed classifies this record as: \"chapter\" or \"book\" for an NCBI Bookshelf record, \"citation\" for an ordinary journal article. Absent when PubMed supplies none.",
+  "type": "string"
+}

Added value: +{
+  "description": "Editors of the containing book, kept out of `authors` so they cannot displace the record's own authors. Absent on a journal article and on a book that credits no editors.",
+  "items": {
+    "description": "One editor, \"Surname Initials\" as ESummary renders it",
+    "type": "string"
+  },
+  "type": "array"
+}

Added value: +{
+  "description": "Publisher of the book an NCBI Bookshelf record belongs to. Present only on a book record; absent on a journal article.",
+  "type": "string"
+}

Previous value: -"Journal source"New value: +"Journal the article appeared in. Absent on an NCBI Bookshelf record, which has no journal — its venue is in `bookTitle` and `publisherName` instead, and `docType` says which kind of record it is."

Added value: +{
+  "description": "Reference-coverage fallbacks that failed instead of answering, so the reference set is unverified rather than confirmed absent. Absent when every provider consulted answered.",
+  "items": {
+    "additionalProperties": false,
+    "description": "One coverage provider that could not be checked",
+    "properties": {
+      "provider": {
+        "description": "Reference-coverage provider that failed",
+        "enum": [
+          "europepmc",
+          "openalex"
+        ],
+        "type": "string"
+      },
+      "reason": {
+        "description": "Declared failure reason, e.g. europepmc_unreachable or provider_disabled",
+        "type": "string"
+      },
+      "retryable": {
+        "description": "Whether a retry can reach this provider",
+        "type": "boolean"
+      }
+    },
+    "required": [
+      "provider",
+      "reason",
+      "retryable"
+    ],
+    "type": "object"
+  },
+  "type": "array"
+}

Previous value: -"Guidance when results are empty, a fallback provider answered, offset overshot, or Europe PMC rows were excluded for carrying no PubMed PMID. Absent on a clean NCBI result page."New value: +"Guidance when results are empty, a fallback provider answered, offset overshot, a fallback provider could not be reached, or upstream rows were excluded for carrying no PubMed PMID. Absent on a clean NCBI result page."

Previous value: -"Total related articles found before windowing. A Europe PMC total may shrink to the PubMed-addressable count once a request window covers the whole upstream set, since rows without a PubMed PMID cannot be returned."New value: +"Total related articles found before windowing. A Europe PMC or OpenAlex total may shrink to the PubMed-addressable count once a request window covers the whole upstream set, since rows without a PubMed PMID cannot be returned."

Previous value: -"Requested PMIDs that did not return article metadata"New value: +"PMIDs PubMed returned no record for, so nothing could be cited for them. That is all this reports: PubMed omits a PMID it does not recognize silently, with no error and no reason, so the absence says nothing about whether the PMID exists. Use `pubmed_search_articles` to find PMIDs that do resolve."

Previous value: -"Author name, typically \"lastname initials\" (e.g., \"mann bj\")"New value: +"Author name, typically \"lastname initials\" (e.g., \"mann bj\"). Cannot contain a pipe (\"|\") or a line break."

Added value: +"^[^|\\r\\n]*$"

Previous value: -"First page number"New value: +"First page number. Cannot contain a pipe (\"|\") or a line break."

Added value: +"^[^|\\r\\n]*$"

Previous value: -"Journal title or ISO abbreviation (e.g., \"proc natl acad sci u s a\")"New value: +"Journal title or ISO abbreviation (e.g., \"proc natl acad sci u s a\"). Cannot contain a pipe (\"|\") or a line break."

Added value: +"^[^|\\r\\n]*$"

Previous value: -"Arbitrary label to track this citation in results. Auto-assigned if omitted."New value: +"Arbitrary label to track this citation in results. Auto-assigned if omitted. Echoed back unchanged and never sent to NCBI, so any character is accepted here."

Previous value: -"Volume number"New value: +"Volume number. Cannot contain a pipe (\"|\") or a line break."

Added value: +"^[^|\\r\\n]*$"

Previous value: -"Publication year (e.g., \"1991\")"New value: +"Publication year (e.g., \"1991\"). Cannot contain a pipe (\"|\") or a line break."

Added value: +"^[^|\\r\\n]*$"

Previous value: -"MeSH descriptor name or free-text term to look up"New value: +"MeSH descriptor name or free-text term to look up. Must carry a term: a blank or whitespace-only value is rejected rather than searched."

Previous value: -"Machine-readable failure mode. Declared by this tool: `queue_full`: Local NCBI request queue is at capacity. `ncbi_unreachable`: NCBI E-utilities is unreachable after all retry attempts. `ncbi_deadline_exceeded`: Total request deadline expired before NCBI returned a response. `ncbi_invalid_response`: NCBI returned a body that could not be parsed (invalid XML/JSON). `ncbi_resource_not_found`: NCBI returned a structured \"not found\" error for the requested ID(s). Other values are possible when a failure originates below the handler."New value: +"Machine-readable failure mode. Declared by this tool: `queue_full`: Local NCBI request queue is at capacity. `ncbi_unreachable`: NCBI E-utilities is unreachable after all retry attempts. `ncbi_deadline_exceeded`: Total request deadline expired before NCBI returned a response. `ncbi_invalid_response`: NCBI returned a body that could not be parsed (invalid XML/JSON). `ncbi_resource_not_found`: NCBI returned a structured \"not found\" error for the requested ID(s). `blank_query`: The query holds no search term once whitespace, and any markup the tool strips first, are removed — so NCBI would receive a blank term. Other values are possible when a failure originates below the handler."

Previous value: -[
-  "queue_full",
-  "ncbi_unreachable",
-  "ncbi_deadline_exceeded",
-  "ncbi_invalid_response",
-  "ncbi_resource_not_found"
-]New value: +[
+  "queue_full",
+  "ncbi_unreachable",
+  "ncbi_deadline_exceeded",
+  "ncbi_invalid_response",
+  "ncbi_resource_not_found",
+  "blank_query"
+]

Previous value: -"PubMed search query (supports full NCBI syntax)"New value: +"PubMed search query (supports full NCBI syntax). Must carry a search term: a value that is blank once markup is stripped is rejected rather than sent to PubMed as an empty term."

Previous value: -"Machine-readable failure mode. Declared by this tool: `queue_full`: Local NCBI request queue is at capacity. `ncbi_unreachable`: NCBI E-utilities is unreachable after all retry attempts. `ncbi_deadline_exceeded`: Total request deadline expired before NCBI returned a response. `ncbi_invalid_response`: NCBI returned a body that could not be parsed (invalid XML/JSON). `ncbi_resource_not_found`: NCBI returned a structured \"not found\" error for the requested ID(s). Other values are possible when a failure originates below the handler."New value: +"Machine-readable failure mode. Declared by this tool: `queue_full`: Local NCBI request queue is at capacity. `ncbi_unreachable`: NCBI E-utilities is unreachable after all retry attempts. `ncbi_deadline_exceeded`: Total request deadline expired before NCBI returned a response. `ncbi_invalid_response`: NCBI returned a body that could not be parsed (invalid XML/JSON). `ncbi_resource_not_found`: NCBI returned a structured \"not found\" error for the requested ID(s). `blank_query`: The query holds no search term once whitespace, and any markup the tool strips first, are removed — so NCBI would receive a blank term. Other values are possible when a failure originates below the handler."

Previous value: -[
-  "queue_full",
-  "ncbi_unreachable",
-  "ncbi_deadline_exceeded",
-  "ncbi_invalid_response",
-  "ncbi_resource_not_found"
-]New value: +[
+  "queue_full",
+  "ncbi_unreachable",
+  "ncbi_deadline_exceeded",
+  "ncbi_invalid_response",
+  "ncbi_resource_not_found",
+  "blank_query"
+]

Previous value: -"Formatted author string"New value: +"Formatted author string — the first three of the record's own authors, then \"et al.\". On an NCBI Bookshelf chapter these are the chapter's authors; the book's editors are reported separately in `editors`."

Added value: +{
+  "description": "Title of the book an NCBI Bookshelf record belongs to, e.g. \"GeneReviews(®)\". Present instead of `source` on a book record; absent on a journal article.",
+  "type": "string"
+}

Added value: +{
+  "description": "What PubMed classifies this record as: \"chapter\" or \"book\" for an NCBI Bookshelf record, \"citation\" for an ordinary journal article. Absent when PubMed supplies none.",
+  "type": "string"
+}

Added value: +{
+  "description": "Editors of the containing book, kept out of `authors` so they cannot displace the record's own authors. Absent on a journal article and on a book that credits no editors.",
+  "items": {
+    "description": "One editor, \"Surname Initials\" as ESummary renders it",
+    "type": "string"
+  },
+  "type": "array"
+}

Added value: +{
+  "description": "Publisher of the book an NCBI Bookshelf record belongs to. Present only on a book record; absent on a journal article.",
+  "type": "string"
+}

Previous value: -"Journal source"New value: +"Journal the article appeared in. Absent on an NCBI Bookshelf record, which has no journal — its venue is in `bookTitle` and `publisherName` instead, and `docType` says which kind of record it is."

Previous value: -"PubMed search query to spell-check"New value: +"PubMed search query to spell-check. Must carry a term: a blank or whitespace-only value is rejected rather than sent to ESpell."

Previous value: -"Machine-readable failure mode. Declared by this tool: `queue_full`: Local NCBI request queue is at capacity. `ncbi_unreachable`: NCBI E-utilities is unreachable after all retry attempts. `ncbi_deadline_exceeded`: Total request deadline expired before NCBI returned a response. `ncbi_invalid_response`: NCBI returned a body that could not be parsed (invalid XML/JSON). `ncbi_resource_not_found`: NCBI returned a structured \"not found\" error for the requested ID(s). Other values are possible when a failure originates below the handler."New value: +"Machine-readable failure mode. Declared by this tool: `queue_full`: Local NCBI request queue is at capacity. `ncbi_unreachable`: NCBI E-utilities is unreachable after all retry attempts. `ncbi_deadline_exceeded`: Total request deadline expired before NCBI returned a response. `ncbi_invalid_response`: NCBI returned a body that could not be parsed (invalid XML/JSON). `ncbi_resource_not_found`: NCBI returned a structured \"not found\" error for the requested ID(s). `blank_query`: The query holds no search term once whitespace, and any markup the tool strips first, are removed — so NCBI would receive a blank term. Other values are possible when a failure originates below the handler."

Previous value: -[
-  "queue_full",
-  "ncbi_unreachable",
-  "ncbi_deadline_exceeded",
-  "ncbi_invalid_response",
-  "ncbi_resource_not_found"
-]New value: +[
+  "queue_full",
+  "ncbi_unreachable",
+  "ncbi_deadline_exceeded",
+  "ncbi_invalid_response",
+  "ncbi_resource_not_found",
+  "blank_query"
+]

Previous value: -"Formatted author string"New value: +"Formatted author string as display-ready plain text — JATS/HTML markup stripped and HTML entities decoded."

Previous value: -"Journal title"New value: +"Journal title as display-ready plain text — JATS/HTML markup stripped and HTML entities decoded."

Previous value: -"Record title"New value: +"Record title as display-ready plain text — JATS/HTML markup stripped and HTML entities decoded."

Previous value: -"Formatted author string"New value: +"Formatted author string as display-ready plain text — JATS/HTML markup stripped and HTML entities decoded."

Previous value: -"Journal title"New value: +"Journal title as display-ready plain text — JATS/HTML markup stripped and HTML entities decoded."

Previous value: -"Article title"New value: +"Article title as display-ready plain text — JATS/HTML markup stripped and HTML entities decoded."

Added value: +{
+  "description": "Opt-in ceiling for the whole response, in characters. Each article is measured as the JSON record it is returned as — title, abstract, authors, journal, MeSH terms, grants, identifiers, every field it carries. Articles are kept in response order until the next one would cross the ceiling; that article and the rest are deferred whole (never partially populated) and listed in `deferred.ids`. Response envelope fields — counts, `unavailablePmids`, `deferred` itself — are not counted. Omit to return every resolved article.",
+  "maximum": 1000000,
+  "minimum": 1,
+  "type": "integer"
+}

Added value: +{
+  "additionalProperties": false,
+  "description": "Continuation state for articles the whole-response budget withheld. Present only when `maxResponseCharacters` deferred at least one article.",
+  "properties": {
+    "deferredCount": {
+      "description": "Articles that resolved but were withheld to stay under the ceiling",
+      "type": "number"
+    },
+    "ids": {
+      "description": "PMIDs of the deferred articles, in response order. Re-call `pubmed_fetch_articles` with these as `pmids` and the same other inputs to retrieve them. Never contains a PMID from `unavailablePmids`.",
+      "items": {
+        "type": "string"
+      },
+      "type": "array"
+    },
+    "maxResponseCharacters": {
+      "description": "The `maxResponseCharacters` ceiling this response was budgeted against",
+      "type": "number"
+    },
+    "nextDeferredCharacters": {
+      "description": "Serialized size of the next deferred article — the first entry in `ids`, where the response stopped. Raise `maxResponseCharacters` to at least this to make progress; a smaller article further down `ids` cannot be reached until this one fits.",
+      "type": "number"
+    },
+    "returnedCharacters": {
+      "description": "Serialized characters the returned article records account for",
+      "type": "number"
+    }
+  },
+  "required": [
+    "maxResponseCharacters",
+    "returnedCharacters",
+    "deferredCount",
+    "ids",
+    "nextDeferredCharacters"
+  ],
+  "type": "object"
+}

Previous value: -"Optional guidance when no articles were returned — points to discovery tools. Absent on successful fetches."New value: +"Optional guidance when no articles were returned — points to discovery tools — or when `maxResponseCharacters` deferred articles, naming how to retrieve them. Absent on successful unbudgeted fetches."

Previous value: -"Number of articles returned"New value: +"Number of articles in this response. Under a `maxResponseCharacters` budget this counts the kept articles only; `deferred.deferredCount` covers the rest."

Added value: +{
+  "description": "True when `maxResponseCharacters` withheld at least one resolved article. Absent when the response carries every article that resolved. The continuation state is in `deferred`.",
+  "type": "boolean"
+}

Previous value: -"PMIDs that returned no article data"New value: +"PMIDs that returned no article data. Reported in full regardless of where a `maxResponseCharacters` cutoff lands — these are misses, not deferrals, and re-requesting them returns nothing."

Previous value: -"Per-article budget for body text, in characters. Counts `source=pmc` section and subsection text, or the `source=unpaywall` `content` body; titles, abstracts, identifiers, and references are never counted or shortened. Applied after `sections`, `maxSections`, and `includeReferences`, so semantic filtering is unaffected. The response-wide ceiling is this value times the number of articles returned. Omit for the full body."New value: +"Per-article budget for body text, in characters. Counts `source=pmc` section and subsection text, or the `source=unpaywall` `content` body; titles, abstracts, identifiers, and references are never counted or shortened. Applied after `sections`, `maxSections`, and `includeReferences`, so semantic filtering is unaffected. This knob alone bounds only bodies: the response-wide ceiling it implies is this value times the number of articles returned, plus every uncounted field. Use `maxResponseCharacters` for a true whole-response ceiling. Omit for the full body."

Added value: +{
+  "description": "Opt-in ceiling for the whole response, in characters — the true response-wide counterpart to the per-article `maxCharacters`. Each article is measured as the JSON record it is returned as, after every filter and the per-article body budget: title, abstract, body sections, references, identifiers, license and source metadata — every field it carries. One ledger covers all tiers, so PMC-, Europe PMC-, and Unpaywall-served articles spend the same budget. Articles are kept in response order until the next one would cross the ceiling; that article and the rest are deferred whole (never partially populated) and listed in `deferred.ids`. Response envelope fields — counts, `unavailable`, `truncation`, `deferred` itself — are not counted. Omit to return every resolved article.",
+  "maximum": 1000000,
+  "minimum": 1,
+  "type": "integer"
+}

Previous value: -[
-  {
-    "additionalProperties": false,
-    "description": "Structured JATS full-text article. `viaSource` records whether the JATS came from NCBI PMC or Europe PMC.",
-    "properties": {
-      "abstract": {
-        "description": "Abstract",
-        "type": "string"
-      },
-      "affiliations": {
-        "description": "Author affiliations",
-        "items": {
-          "type": "string"
-        },
-        "type": "array"
-      },
-      "articleType": {
-        "description": "Article type",
-        "type": "string"
-      },
-      "authors": {
-        "description": "Authors",
-        "items": {
-          "additionalProperties": false,
-          "description": "Author entry",
-          "properties": {
-            "collectiveName": {
-              "description": "Group name",
-              "type": "string"
-            },
-            "givenNames": {
-              "description": "Given names",
-              "type": "string"
-            },
-            "lastName": {
-              "description": "Last name",
-              "type": "string"
-            }
-          },
-          "type": "object"
-        },
-        "type": "array"
-      },
-      "doi": {
-        "description": "DOI, cased as the tier that served this record reports it (NCBI PMC, Europe PMC, or Unpaywall). DOIs are case-insensitive by spec and no case normalization is applied here, so casing can differ between tiers and from other tools — compare case-insensitively.",
-        "type": "string"
-      },
-      "epmcId": {
-        "description": "Europe PMC record id — present when `viaSource` is `europepmc`",
-        "type": "string"
-      },
-      "epmcSource": {
-        "description": "Europe PMC source code when `viaSource` is `europepmc`. Common values: `MED` (PubMed-derived), `PMC` (PMC counterpart), `PPR` (preprint), `PAT` (patent), `AGR` (Agricola), plus less common codes (`CTX`, `CBA`, `ETH`, `HIR`). Treat as opaque — EPMC may introduce new codes.",
-        "type": "string"
-      },
-      "journal": {
-        "additionalProperties": false,
-        "description": "Journal information",
-        "properties": {
-          "issn": {
-            "description": "ISSN",
-            "type": "string"
-          },
-          "issue": {
-            "description": "Issue number",
-            "type": "string"
-          },
-          "pages": {
-            "description": "Page range",
-            "type": "string"
-          },
-          "title": {
-            "description": "Journal title",
-            "type": "string"
-          },
-          "volume": {
-            "description": "Volume number",
-            "type": "string"
-          }
-        },
-        "type": "object"
-      },
-      "keywords": {
-        "description": "Keywords",
-        "items": {
-          "type": "string"
-        },
-        "type": "array"
-      },
-      "pmcId": {
-        "description": "PMC ID — present for NCBI PMC records and Europe PMC entries that have a PMC counterpart. Absent for EPMC-only records like preprints; use `epmcId` in that case.",
-        "type": "string"
-      },
-      "pmcUrl": {
-        "description": "PMC URL — derived from `pmcId` when present",
-        "type": "string"
-      },
-      "pmid": {
-        "description": "PubMed ID",
-        "type": "string"
-      },
-      "publicationDate": {
-        "additionalProperties": false,
-        "description": "Publication date",
-        "properties": {
-          "day": {
-            "description": "Publication day",
-            "type": "string"
-          },
-          "month": {
-            "description": "Publication month",
-            "type": "string"
-          },
-          "year": {
-            "description": "Publication year",
-            "type": "string"
-          }
-        },
-        "type": "object"
-      },
-      "pubmedUrl": {
-        "description": "PubMed URL",
-        "type": "string"
-      },
-      "references": {
-        "description": "Reference list",
-        "items": {
-          "additionalProperties": false,
-          "description": "Reference entry",
-          "properties": {
-            "citation": {
-              "description": "Citation text",
-              "type": "string"
-            },
-            "id": {
-              "description": "Reference ID",
-              "type": "string"
-            },
-            "label": {
-              "description": "Reference label",
-              "type": "string"
-            }
-          },
-          "required": [
-            "citation"
-          ],
-          "type": "object"
-        },
-        "type": "array"
-      },
-      "sections": {
-        "description": "Article body sections",
-        "items": {
-          "additionalProperties": false,
-          "description": "Article body section",
-          "properties": {
-            "label": {
-              "description": "Section label",
-              "type": "string"
-            },
-            "subsections": {
-              "description": "Nested subsections",
-              "items": {
-                "additionalProperties": false,
-                "description": "Article subsection",
-                "properties": {
-                  "label": {
-                    "description": "Subsection label",
-                    "type": "string"
-                  },
-                  "text": {
-                    "description": "Subsection body text",
-                    "type": "string"
-                  },
-                  "title": {
-                    "description": "Subsection heading",
-                    "type": "string"
-                  }
-                },
-                "required": [
-                  "text"
-                ],
-                "type": "object"
-              },
-              "type": "array"
-            },
-            "text": {
-              "description": "Section body text",
-              "type": "string"
-            },
-            "title": {
-              "description": "Section heading",
-              "type": "string"
-            }
-          },
-          "required": [
-            "text"
-          ],
-          "type": "object"
-        },
-        "type": "array"
-      },
-      "source": {
-        "const": "pmc",
-        "description": "Structured JATS — same DTD whether sourced from NCBI PMC or Europe PMC",
-        "type": "string"
-      },
-      "title": {
-        "description": "Article title",
-        "type": "string"
-      },
-      "viaSource": {
-        "description": "Which layer produced the JATS: `pmc` for NCBI PMC EFetch (db=pmc), `europepmc` for Europe PMC `fullTextXML`. Both paths return the same JATS shape; the discriminator records origin for observability and license attribution.",
-        "enum": [
-          "pmc",
-          "europepmc"
-        ],
-        "type": "string"
-      }
-    },
-    "required": [
-      "source",
-      "viaSource",
-      "sections"
-    ],
-    "type": "object"
-  },
-  {
-    "additionalProperties": false,
-    "description": "Best-effort full text from an open-access copy",
-    "properties": {
-      "content": {
-        "description": "Full article text — Markdown or plain text per `contentFormat`",
-        "type": "string"
-      },
-      "contentFormat": {
-        "description": "How `content` was extracted. html-markdown: Defuddle extracted Markdown from an HTML landing page; light section structure may survive but is not guaranteed. pdf-text: unpdf extracted plain text from a PDF; no section, reference, or heading structure.",
-        "enum": [
-          "html-markdown",
-          "pdf-text"
-        ],
-        "type": "string"
-      },
-      "doi": {
-        "description": "DOI used to locate the open-access copy",
-        "type": "string"
-      },
-      "hostType": {
-        "description": "`publisher` or `repository` — where the OA copy is hosted",
-        "type": "string"
-      },
-      "license": {
-        "description": "License identifier from Unpaywall (e.g. cc-by, cc0)",
-        "type": "string"
-      },
-      "pmcId": {
-        "description": "PMC ID this article was requested under, in `PMC<digits>` form — present for `pmcids` input, absent for `pmids` and `dois` input. Ties the article back to the requested identifier, which `unavailable[]` keys on for the ids that found nothing.",
-        "type": "string"
-      },
-      "pmid": {
-        "description": "PubMed ID when input was `pmids`; absent for `pmcids` and `dois` input",
-        "type": "string"
-      },
-      "pubmedUrl": {
-        "description": "PubMed URL — present when `pmid` is set",
-        "type": "string"
-      },
-      "source": {
-        "const": "unpaywall",
-        "description": "Content fetched from an open-access copy indexed by Unpaywall. Best-effort — structural fidelity depends on `contentFormat`.",
-        "type": "string"
-      },
-      "sourceUrl": {
-        "description": "URL the content was fetched from",
-        "type": "string"
-      },
-      "title": {
-        "description": "Detected article title when present",
-        "type": "string"
-      },
-      "totalPages": {
-        "description": "Page count reported by the PDF extractor; absent for HTML",
-        "type": "number"
-      },
-      "version": {
-        "description": "OA version: submittedVersion | acceptedVersion | publishedVersion",
-        "type": "string"
-      },
-      "viaSource": {
-        "const": "unpaywall",
-        "description": "Layer that produced this article. Constant `unpaywall` for this branch.",
-        "type": "string"
-      },
-      "wordCount": {
-        "description": "Approximate word count reported by the HTML extractor; absent for PDFs",
-        "type": "number"
-      }
-    },
-    "required": [
-      "source",
-      "viaSource",
-      "contentFormat",
-      "doi",
-      "sourceUrl",
-      "content"
-    ],
-    "type": "object"
-  }
-]New value: +[
+  {
+    "additionalProperties": false,
+    "description": "Structured JATS full-text article. `viaSource` records whether the JATS came from NCBI PMC or Europe PMC.",
+    "properties": {
+      "abstract": {
+        "description": "Abstract",
+        "type": "string"
+      },
+      "affiliations": {
+        "description": "Author affiliations",
+        "items": {
+          "type": "string"
+        },
+        "type": "array"
+      },
+      "articleType": {
+        "description": "Article type",
+        "type": "string"
+      },
+      "authors": {
+        "description": "Authors",
+        "items": {
+          "additionalProperties": false,
+          "description": "Author entry",
+          "properties": {
+            "collectiveName": {
+              "description": "Group name",
+              "type": "string"
+            },
+            "givenNames": {
+              "description": "Given names",
+              "type": "string"
+            },
+            "lastName": {
+              "description": "Last name",
+              "type": "string"
+            }
+          },
+          "type": "object"
+        },
+        "type": "array"
+      },
+      "doi": {
+        "description": "DOI, cased as the tier that served this record reports it (NCBI PMC, Europe PMC, or Unpaywall). DOIs are case-insensitive by spec and no case normalization is applied here, so casing can differ between tiers and from other tools — compare case-insensitively.",
+        "type": "string"
+      },
+      "epmcId": {
+        "description": "Europe PMC record id — present when `viaSource` is `europepmc`",
+        "type": "string"
+      },
+      "epmcSource": {
+        "description": "Europe PMC source code when `viaSource` is `europepmc`. Common values: `MED` (PubMed-derived), `PMC` (PMC counterpart), `PPR` (preprint), `PAT` (patent), `AGR` (Agricola), plus less common codes (`CTX`, `CBA`, `ETH`, `HIR`). Treat as opaque — EPMC may introduce new codes.",
+        "type": "string"
+      },
+      "journal": {
+        "additionalProperties": false,
+        "description": "Journal information",
+        "properties": {
+          "issn": {
+            "description": "ISSN",
+            "type": "string"
+          },
+          "issue": {
+            "description": "Issue number",
+            "type": "string"
+          },
+          "pages": {
+            "description": "Page range",
+            "type": "string"
+          },
+          "title": {
+            "description": "Journal title",
+            "type": "string"
+          },
+          "volume": {
+            "description": "Volume number",
+            "type": "string"
+          }
+        },
+        "type": "object"
+      },
+      "keywords": {
+        "description": "Keywords",
+        "items": {
+          "type": "string"
+        },
+        "type": "array"
+      },
+      "pmcId": {
+        "description": "PMC ID — present for NCBI PMC records and Europe PMC entries that have a PMC counterpart. Absent for EPMC-only records like preprints; use `epmcId` in that case.",
+        "type": "string"
+      },
+      "pmcUrl": {
+        "description": "PMC URL — derived from `pmcId` when present",
+        "type": "string"
+      },
+      "pmid": {
+        "description": "PubMed ID",
+        "type": "string"
+      },
+      "publicationDate": {
+        "additionalProperties": false,
+        "description": "Publication date",
+        "properties": {
+          "day": {
+            "description": "Publication day",
+            "type": "string"
+          },
+          "month": {
+            "description": "Publication month",
+            "type": "string"
+          },
+          "year": {
+            "description": "Publication year",
+            "type": "string"
+          }
+        },
+        "type": "object"
+      },
+      "pubmedUrl": {
+        "description": "PubMed URL",
+        "type": "string"
+      },
+      "references": {
+        "description": "Reference list",
+        "items": {
+          "additionalProperties": false,
+          "description": "Reference entry",
+          "properties": {
+            "citation": {
+              "description": "Citation text",
+              "type": "string"
+            },
+            "id": {
+              "description": "Reference ID",
+              "type": "string"
+            },
+            "label": {
+              "description": "Reference label",
+              "type": "string"
+            }
+          },
+          "required": [
+            "citation"
+          ],
+          "type": "object"
+        },
+        "type": "array"
+      },
+      "sections": {
+        "description": "Article body sections",
+        "items": {
+          "additionalProperties": false,
+          "description": "Article body section",
+          "properties": {
+            "label": {
+              "description": "Section label",
+              "type": "string"
+            },
+            "subsections": {
+              "description": "Nested subsections",
+              "items": {
+                "additionalProperties": false,
+                "description": "Article subsection",
+                "properties": {
+                  "label": {
+                    "description": "Subsection label",
+                    "type": "string"
+                  },
+                  "text": {
+                    "description": "Subsection body text. Sections nested deeper than this level are folded in here in document order, each heading rendered on its own line above its text.",
+                    "type": "string"
+                  },
+                  "title": {
+                    "description": "Subsection heading",
+                    "type": "string"
+                  }
+                },
+                "required": [
+                  "text"
+                ],
+                "type": "object"
+              },
+              "type": "array"
+            },
+            "text": {
+              "description": "Section body text",
+              "type": "string"
+            },
+            "title": {
+              "description": "Section heading",
+              "type": "string"
+            }
+          },
+          "required": [
+            "text"
+          ],
+          "type": "object"
+        },
+        "type": "array"
+      },
+      "source": {
+        "const": "pmc",
+        "description": "Structured JATS — same DTD whether sourced from NCBI PMC or Europe PMC",
+        "type": "string"
+      },
+      "title": {
+        "description": "Article title",
+        "type": "string"
+      },
+      "viaSource": {
+        "description": "Which layer produced the JATS: `pmc` for NCBI PMC EFetch (db=pmc), `europepmc` for Europe PMC `fullTextXML`. Both paths return the same JATS shape; the discriminator records origin for observability and license attribution.",
+        "enum": [
+          "pmc",
+          "europepmc"
+        ],
+        "type": "string"
+      }
+    },
+    "required": [
+      "source",
+      "viaSource",
+      "sections"
+    ],
+    "type": "object"
+  },
+  {
+    "additionalProperties": false,
+    "description": "Best-effort full text from an open-access copy",
+    "properties": {
+      "content": {
+        "description": "Full article text — Markdown or plain text per `contentFormat`",
+        "type": "string"
+      },
+      "contentFormat": {
+        "description": "How `content` was extracted. html-markdown: Defuddle extracted Markdown from an HTML landing page; light section structure may survive but is not guaranteed. pdf-text: unpdf extracted plain text from a PDF; no section, reference, or heading structure.",
+        "enum": [
+          "html-markdown",
+          "pdf-text"
+        ],
+        "type": "string"
+      },
+      "doi": {
+        "description": "DOI used to locate the open-access copy",
+        "type": "string"
+      },
+      "hostType": {
+        "description": "`publisher` or `repository` — where the OA copy is hosted",
+        "type": "string"
+      },
+      "license": {
+        "description": "License identifier from Unpaywall (e.g. cc-by, cc0)",
+        "type": "string"
+      },
+      "pmcId": {
+        "description": "PMC ID this article was requested under, in `PMC<digits>` form — present for `pmcids` input, absent for `pmids` and `dois` input. Ties the article back to the requested identifier, which `unavailable[]` keys on for the ids that found nothing.",
+        "type": "string"
+      },
+      "pmid": {
+        "description": "PubMed ID when input was `pmids`; absent for `pmcids` and `dois` input",
+        "type": "string"
+      },
+      "pubmedUrl": {
+        "description": "PubMed URL — present when `pmid` is set",
+        "type": "string"
+      },
+      "source": {
+        "const": "unpaywall",
+        "description": "Content fetched from an open-access copy indexed by Unpaywall. Best-effort — structural fidelity depends on `contentFormat`.",
+        "type": "string"
+      },
+      "sourceUrl": {
+        "description": "URL the content was fetched from",
+        "type": "string"
+      },
+      "title": {
+        "description": "Detected article title when present",
+        "type": "string"
+      },
+      "totalPages": {
+        "description": "Page count reported by the PDF extractor; absent for HTML",
+        "type": "number"
+      },
+      "version": {
+        "description": "OA version: submittedVersion | acceptedVersion | publishedVersion",
+        "type": "string"
+      },
+      "viaSource": {
+        "const": "unpaywall",
+        "description": "Layer that produced this article. Constant `unpaywall` for this branch.",
+        "type": "string"
+      },
+      "wordCount": {
+        "description": "Approximate word count reported by the HTML extractor; absent for PDFs",
+        "type": "number"
+      }
+    },
+    "required": [
+      "source",
+      "viaSource",
+      "contentFormat",
+      "doi",
+      "sourceUrl",
+      "content"
+    ],
+    "type": "object"
+  }
+]

Added value: +{
+  "additionalProperties": false,
+  "description": "Continuation state for articles the whole-response budget withheld. Present only when `maxResponseCharacters` deferred at least one article.",
+  "properties": {
+    "deferredCount": {
+      "description": "Articles the chain resolved but withheld to stay under the ceiling",
+      "type": "number"
+    },
+    "idType": {
+      "description": "Which input branch the deferred ids belong to — re-submit them as `pmids`, `pmcids`, or `dois` respectively. Matches the `idType` on `unavailable` entries.",
+      "enum": [
+        "pmid",
+        "pmcid",
+        "doi"
+      ],
+      "type": "string"
+    },
+    "ids": {
+      "description": "Identifiers of the deferred articles, in response order, keyed as they were requested (PMC IDs in `PMC<digits>` form). Re-call `pubmed_fetch_fulltext` with these under the `idType` branch and the same other inputs. Never contains an id from `unavailable`.",
+      "items": {
+        "type": "string"
+      },
+      "type": "array"
+    },
+    "maxResponseCharacters": {
+      "description": "The `maxResponseCharacters` ceiling this response was budgeted against",
+      "type": "number"
+    },
+    "nextDeferredCharacters": {
+      "description": "Serialized size of the next deferred article — the first entry in `ids`, where the response stopped. Raise `maxResponseCharacters` to at least this to make progress; a smaller article further down `ids` cannot be reached until this one fits.",
+      "type": "number"
+    },
+    "returnedCharacters": {
+      "description": "Serialized characters the returned article records account for",
+      "type": "number"
+    }
+  },
+  "required": [
+    "maxResponseCharacters",
+    "returnedCharacters",
+    "deferredCount",
+    "idType",
+    "ids",
+    "nextDeferredCharacters"
+  ],
+  "type": "object"
+}

Previous value: -"Optional guidance for a partial or empty body. A `sections`-filter miss names the requested terms and affected article id(s) and suggests retrying without `sections` or using broader headings. A metadata-only record names the id(s) the chain could retrieve as front matter only and points at `pubmed_fetch_articles` for the abstract. A budgeted response names the characters returned versus carried and points at `truncation`. Absent when none of those applies."New value: +"Optional guidance for a partial or empty body. A `sections`-filter miss names the requested terms and affected article id(s) and suggests retrying without `sections` or using broader headings. A metadata-only record names the id(s) the chain could retrieve as front matter only and points at `pubmed_fetch_articles` for the abstract. A budgeted response names the characters returned versus carried and points at `truncation`. A response-wide budget that deferred articles names the ids to re-request. Absent when none of those applies."

Previous value: -"Number of articles returned"New value: +"Number of articles in this response. Under a `maxResponseCharacters` budget this counts the kept articles only; `deferred.deferredCount` covers the rest."

Previous value: -"True when a character budget shortened at least one returned body. Absent when every returned article carries its full post-filter body. The per-article accounting is in `truncation`."New value: +"True when a character budget shortened at least one returned body, or withheld a whole article. Absent when every resolved article is present with its full post-filter body. The per-article body accounting is in `truncation`; the withheld ids are in `deferred`."

Previous value: -"Per-identifier explanations for any requested PMIDs, PMCIDs, or DOIs with no returnable full text. `idType` discriminates which branch the id came from."New value: +"Per-identifier explanations for any requested PMIDs, PMCIDs, or DOIs with no returnable full text. `idType` discriminates which branch the id came from. Distinct from `deferred`: nothing here is retrievable by re-calling, and an id never appears in both."

Previous value: -"Why no full text was returned. not-found: upstream returned no record for this ID. no-pmc-fallback-disabled: every tier was skipped (`triedTiers` is all `not-attempted`) — typically because EPMC (`EUROPEPMC_ENABLED`) and Unpaywall (`UNPAYWALL_EMAIL`) are not configured. no-epmc-fulltext: EPMC indexed the record but publishes no fullTextXML. no-body: the record was retrieved but carries front matter and abstract only, with no body sections — use `pubmed_fetch_articles` for the metadata. no-doi: no DOI to query Unpaywall. no-oa: Unpaywall has no OA copy. fetch-failed: download failed. parse-failed: extraction empty. service-error: upstream server failure (threw, timed out, or returned malformed data)."New value: +"Why no full text was returned — the most specific signal any tier that answered reported. not-found: upstream returned no record for this ID. no-pmc-fallback-disabled: every tier was skipped (`triedTiers` is all `not-attempted`) — typically because EPMC (`EUROPEPMC_ENABLED`) and Unpaywall (`UNPAYWALL_EMAIL`) are not configured. no-epmc-fulltext: EPMC indexed the record but publishes no fullTextXML. no-body: the record was retrieved but carries front matter and abstract only, with no body sections — use `pubmed_fetch_articles` for the metadata. no-doi: no DOI to query Unpaywall. no-oa: Unpaywall has no OA copy. fetch-failed: download failed. parse-failed: extraction empty. service-error: upstream server failure (threw, timed out, or returned malformed data). A reason never means the chain ran to completion — read `unqueriedTiers` for that."

Added value: +{
+  "description": "Tiers the chain skipped because this deployment has not configured them, and that could have served this id — the search was incomplete, and a deployment with these tiers configured may still resolve the id. `triedTiers` carries which environment variable each one is waiting on. Absent when every tier that could have served the id was actually queried; a tier skipped because it was inapplicable to this id (no DOI for Unpaywall) is never listed.",
+  "items": {
+    "description": "A fallback tier this deployment has not configured",
+    "enum": [
+      "europepmc",
+      "unpaywall"
+    ],
+    "type": "string"
+  },
+  "type": "array"
+}

Previous value: -"Machine-readable failure mode. Declared by this tool: `queue_full`: Local NCBI request queue is at capacity. `ncbi_unreachable`: NCBI E-utilities is unreachable after all retry attempts. `ncbi_deadline_exceeded`: Total request deadline expired before NCBI returned a response. `ncbi_invalid_response`: NCBI returned a body that could not be parsed (invalid XML/JSON). `ncbi_resource_not_found`: NCBI returned a structured \"not found\" error for the requested ID(s). `europepmc_unreachable`: Europe PMC was unreachable after all retry attempts. `europepmc_invalid_response`: Europe PMC returned a body that could not be parsed (invalid JSON or XML). `europepmc_invalid_input`: Europe PMC rejected the request input (empty query, unknown sort field, malformed parameter). `openalex_unreachable`: OpenAlex was unreachable after all retry attempts. `openalex_invalid_response`: OpenAlex returned a body that could not be parsed (invalid JSON). Other values are possible when a failure originates below the handler."New value: +"Machine-readable failure mode. Declared by this tool: `queue_full`: Local NCBI request queue is at capacity. `ncbi_unreachable`: NCBI E-utilities is unreachable after all retry attempts. `ncbi_deadline_exceeded`: Total request deadline expired before NCBI returned a response. `ncbi_invalid_response`: NCBI returned a body that could not be parsed (invalid XML/JSON). `ncbi_resource_not_found`: NCBI returned a structured \"not found\" error for the requested ID(s). `europepmc_unreachable`: Europe PMC was unreachable after all retry attempts. `europepmc_invalid_response`: Europe PMC returned a body that could not be parsed (invalid JSON or XML). `europepmc_invalid_input`: Europe PMC rejected the request input (empty query, unknown sort field, malformed parameter). `openalex_unreachable`: OpenAlex was unreachable after all retry attempts. `openalex_invalid_response`: OpenAlex returned a body that could not be parsed (invalid JSON). `all_providers_failed`: Every provider eligible for the requested relationship failed; none answered. Other values are possible when a failure originates below the handler."

Previous value: -[
-  "queue_full",
-  "ncbi_unreachable",
-  "ncbi_deadline_exceeded",
-  "ncbi_invalid_response",
-  "ncbi_resource_not_found",
-  "europepmc_unreachable",
-  "europepmc_invalid_response",
-  "europepmc_invalid_input",
-  "openalex_unreachable",
-  "openalex_invalid_response"
-]New value: +[
+  "queue_full",
+  "ncbi_unreachable",
+  "ncbi_deadline_exceeded",
+  "ncbi_invalid_response",
+  "ncbi_resource_not_found",
+  "europepmc_unreachable",
+  "europepmc_invalid_response",
+  "europepmc_invalid_input",
+  "openalex_unreachable",
+  "openalex_invalid_response",
+  "all_providers_failed"
+]

Previous value: -"Guidance when results are empty, a fallback provider answered, or offset overshot. Absent on a clean NCBI result page."New value: +"Guidance when results are empty, a fallback provider answered, offset overshot, or Europe PMC rows were excluded for carrying no PubMed PMID. Absent on a clean NCBI result page."

Previous value: -"Total related articles found before windowing"New value: +"Total related articles found before windowing. A Europe PMC total may shrink to the PubMed-addressable count once a request window covers the whole upstream set, since rows without a PubMed PMID cannot be returned."

Previous value: -"http://json-schema.org/draft-07/schema#"New value: +"https://json-schema.org/draft/2020-12/schema"

Added value: +false

Previous value: -"http://json-schema.org/draft-07/schema#"New value: +"https://json-schema.org/draft/2020-12/schema"

Added value: +[
+  {
+    "not": {
+      "required": [
+        "error"
+      ]
+    },
+    "required": [
+      "records",
+      "totalConverted",
+      "totalSubmitted"
+    ]
+  },
+  {
+    "required": [
+      "error"
+    ]
+  }
+]

Added value: +{
+  "additionalProperties": {},
+  "description": "Present when the call failed. Absent on success.",
+  "properties": {
+    "code": {
+      "description": "JSON-RPC error code for this failure.",
+      "maximum": 9007199254740991,
+      "minimum": -9007199254740991,
+      "type": "integer"
+    },
+    "data": {
+      "additionalProperties": {},
+      "properties": {
+        "reason": {
+          "description": "Machine-readable failure mode. Declared by this tool: `queue_full`: Local NCBI request queue is at capacity. `ncbi_unreachable`: NCBI E-utilities is unreachable after all retry attempts. `ncbi_deadline_exceeded`: Total request deadline expired before NCBI returned a response. `ncbi_invalid_response`: NCBI returned a body that could not be parsed (invalid XML/JSON). `ncbi_resource_not_found`: NCBI returned a structured \"not found\" error for the requested ID(s). Other values are possible when a failure originates below the handler.",
+          "examples": [
+            "queue_full",
+            "ncbi_unreachable",
+            "ncbi_deadline_exceeded",
+            "ncbi_invalid_response",
+            "ncbi_resource_not_found"
+          ],
+          "type": "string"
+        },
+        "recovery": {
+          "additionalProperties": {},
+          "description": "Actionable next step for the caller.",
+          "properties": {
+            "hint": {
+              "type": "string"
+            }
+          },
+          "required": [
+            "hint"
+          ],
+          "type": "object"
+        },
+        "retryable": {
+          "description": "Whether retrying may succeed.",
+          "type": "boolean"
+        }
+      },
+      "type": "object"
+    },
+    "message": {
+      "description": "Human-readable description of what went wrong.",
+      "type": "string"
+    }
+  },
+  "required": [
+    "code",
+    "message"
+  ],
+  "type": "object"
+}

Removed value: -[
-  "records",
-  "totalConverted",
-  "totalSubmitted"
-]

Previous value: -"http://json-schema.org/draft-07/schema#"New value: +"https://json-schema.org/draft/2020-12/schema"

Added value: +false

Previous value: -"http://json-schema.org/draft-07/schema#"New value: +"https://json-schema.org/draft/2020-12/schema"

Added value: +[
+  {
+    "not": {
+      "required": [
+        "error"
+      ]
+    },
+    "required": [
+      "records"
+    ]
+  },
+  {
+    "required": [
+      "error"
+    ]
+  }
+]

Added value: +{
+  "additionalProperties": {},
+  "description": "Present when the call failed. Absent on success.",
+  "properties": {
+    "code": {
+      "description": "JSON-RPC error code for this failure.",
+      "maximum": 9007199254740991,
+      "minimum": -9007199254740991,
+      "type": "integer"
+    },
+    "data": {
+      "additionalProperties": {},
+      "properties": {
+        "reason": {
+          "description": "Machine-readable failure mode. Declared by this tool: `europepmc_unreachable`: Europe PMC was unreachable after all retry attempts. `europepmc_invalid_response`: Europe PMC returned a body that could not be parsed (invalid JSON or XML). `europepmc_invalid_input`: Europe PMC rejected the request input (empty query, unknown sort field, malformed parameter). `europepmc_disabled`: Europe PMC service is disabled via EUROPEPMC_ENABLED=false. Other values are possible when a failure originates below the handler.",
+          "examples": [
+            "europepmc_unreachable",
+            "europepmc_invalid_response",
+            "europepmc_invalid_input",
+            "europepmc_disabled"
+          ],
+          "type": "string"
+        },
+        "recovery": {
+          "additionalProperties": {},
+          "description": "Actionable next step for the caller.",
+          "properties": {
+            "hint": {
+              "type": "string"
+            }
+          },
+          "required": [
+            "hint"
+          ],
+          "type": "object"
+        },
+        "retryable": {
+          "description": "Whether retrying may succeed.",
+          "type": "boolean"
+        }
+      },
+      "type": "object"
+    },
+    "message": {
+      "description": "Human-readable description of what went wrong.",
+      "type": "string"
+    }
+  },
+  "required": [
+    "code",
+    "message"
+  ],
+  "type": "object"
+}

Removed value: -[
-  "records"
-]

Previous value: -"http://json-schema.org/draft-07/schema#"New value: +"https://json-schema.org/draft/2020-12/schema"

Added value: +false

Previous value: -"http://json-schema.org/draft-07/schema#"New value: +"https://json-schema.org/draft/2020-12/schema"

Added value: +[
+  {
+    "not": {
+      "required": [
+        "error"
+      ]
+    },
+    "required": [
+      "hits",
+      "cursorMark",
+      "searchUrl",
+      "query",
+      "totalCount",
+      "appliedSources"
+    ]
+  },
+  {
+    "required": [
+      "error"
+    ]
+  }
+]

Added value: +{
+  "additionalProperties": {},
+  "description": "Present when the call failed. Absent on success.",
+  "properties": {
+    "code": {
+      "description": "JSON-RPC error code for this failure.",
+      "maximum": 9007199254740991,
+      "minimum": -9007199254740991,
+      "type": "integer"
+    },
+    "data": {
+      "additionalProperties": {},
+      "properties": {
+        "reason": {
+          "description": "Machine-readable failure mode. Declared by this tool: `europepmc_unreachable`: Europe PMC was unreachable after all retry attempts. `europepmc_invalid_response`: Europe PMC returned a body that could not be parsed (invalid JSON or XML). `europepmc_invalid_input`: Europe PMC rejected the request input (empty query, unknown sort field, malformed parameter). `europepmc_disabled`: Europe PMC service is disabled via EUROPEPMC_ENABLED=false. Other values are possible when a failure originates below the handler.",
+          "examples": [
+            "europepmc_unreachable",
+            "europepmc_invalid_response",
+            "europepmc_invalid_input",
+            "europepmc_disabled"
+          ],
+          "type": "string"
+        },
+        "recovery": {
+          "additionalProperties": {},
+          "description": "Actionable next step for the caller.",
+          "properties": {
+            "hint": {
+              "type": "string"
+            }
+          },
+          "required": [
+            "hint"
+          ],
+          "type": "object"
+        },
+        "retryable": {
+          "description": "Whether retrying may succeed.",
+          "type": "boolean"
+        }
+      },
+      "type": "object"
+    },
+    "message": {
+      "description": "Human-readable description of what went wrong.",
+      "type": "string"
+    }
+  },
+  "required": [
+    "code",
+    "message"
+  ],
+  "type": "object"
+}

Removed value: -[
-  "hits",
-  "cursorMark",
-  "searchUrl",
-  "query",
-  "totalCount",
-  "appliedSources"
-]

Previous value: -"http://json-schema.org/draft-07/schema#"New value: +"https://json-schema.org/draft/2020-12/schema"

Added value: +false

Previous value: -"http://json-schema.org/draft-07/schema#"New value: +"https://json-schema.org/draft/2020-12/schema"

Added value: +[
+  {
+    "not": {
+      "required": [
+        "error"
+      ]
+    },
+    "required": [
+      "articles",
+      "totalReturned"
+    ]
+  },
+  {
+    "required": [
+      "error"
+    ]
+  }
+]

Added value: +{
+  "additionalProperties": {},
+  "description": "Present when the call failed. Absent on success.",
+  "properties": {
+    "code": {
+      "description": "JSON-RPC error code for this failure.",
+      "maximum": 9007199254740991,
+      "minimum": -9007199254740991,
+      "type": "integer"
+    },
+    "data": {
+      "additionalProperties": {},
+      "properties": {
+        "reason": {
+          "description": "Machine-readable failure mode. Declared by this tool: `queue_full`: Local NCBI request queue is at capacity. `ncbi_unreachable`: NCBI E-utilities is unreachable after all retry attempts. `ncbi_deadline_exceeded`: Total request deadline expired before NCBI returned a response. `ncbi_invalid_response`: NCBI returned a body that could not be parsed (invalid XML/JSON). `ncbi_resource_not_found`: NCBI returned a structured \"not found\" error for the requested ID(s). `invalid_efetch_response`: NCBI EFetch returned a payload missing the PubmedArticleSet wrapper. Other values are possible when a failure originates below the handler.",
+          "examples": [
+            "queue_full",
+            "ncbi_unreachable",
+            "ncbi_deadline_exceeded",
+            "ncbi_invalid_response",
+            "ncbi_resource_not_found",
+            "invalid_efetch_response"
+          ],
+          "type": "string"
+        },
+        "recovery": {
+          "additionalProperties": {},
+          "description": "Actionable next step for the caller.",
+          "properties": {
+            "hint": {
+              "type": "string"
+            }
+          },
+          "required": [
+            "hint"
+          ],
+          "type": "object"
+        },
+        "retryable": {
+          "description": "Whether retrying may succeed.",
+          "type": "boolean"
+        }
+      },
+      "type": "object"
+    },
+    "message": {
+      "description": "Human-readable description of what went wrong.",
+      "type": "string"
+    }
+  },
+  "required": [
+    "code",
+    "message"
+  ],
+  "type": "object"
+}

Removed value: -[
-  "articles",
-  "totalReturned"
-]

Previous value: -"http://json-schema.org/draft-07/schema#"New value: +"https://json-schema.org/draft/2020-12/schema"

Added value: +false

Previous value: -"http://json-schema.org/draft-07/schema#"New value: +"https://json-schema.org/draft/2020-12/schema"

Added value: +[
+  {
+    "not": {
+      "required": [
+        "error"
+      ]
+    },
+    "required": [
+      "articles",
+      "totalReturned"
+    ]
+  },
+  {
+    "required": [
+      "error"
+    ]
+  }
+]

Added value: +{
+  "additionalProperties": {},
+  "description": "Present when the call failed. Absent on success.",
+  "properties": {
+    "code": {
+      "description": "JSON-RPC error code for this failure.",
+      "maximum": 9007199254740991,
+      "minimum": -9007199254740991,
+      "type": "integer"
+    },
+    "data": {
+      "additionalProperties": {},
+      "properties": {
+        "reason": {
+          "description": "Machine-readable failure mode. Declared by this tool: `queue_full`: Local NCBI request queue is at capacity. `ncbi_unreachable`: NCBI E-utilities is unreachable after all retry attempts. `ncbi_deadline_exceeded`: Total request deadline expired before NCBI returned a response. `ncbi_invalid_response`: NCBI returned a body that could not be parsed (invalid XML/JSON). `ncbi_resource_not_found`: NCBI returned a structured \"not found\" error for the requested ID(s). `unpaywall_unreachable`: Unpaywall was unreachable when resolving a DOI or fetching content. `europepmc_unreachable`: Europe PMC was unreachable after all retry attempts. `europepmc_invalid_response`: Europe PMC returned a body that could not be parsed (invalid JSON or XML). `europepmc_invalid_input`: Europe PMC rejected the request input (empty query, unknown sort field, malformed parameter). Other values are possible when a failure originates below the handler.",
+          "examples": [
+            "queue_full",
+            "ncbi_unreachable",
+            "ncbi_deadline_exceeded",
+            "ncbi_invalid_response",
+            "ncbi_resource_not_found",
+            "unpaywall_unreachable",
+            "europepmc_unreachable",
+            "europepmc_invalid_response",
+            "europepmc_invalid_input"
+          ],
+          "type": "string"
+        },
+        "recovery": {
+          "additionalProperties": {},
+          "description": "Actionable next step for the caller.",
+          "properties": {
+            "hint": {
+              "type": "string"
+            }
+          },
+          "required": [
+            "hint"
+          ],
+          "type": "object"
+        },
+        "retryable": {
+          "description": "Whether retrying may succeed.",
+          "type": "boolean"
+        }
+      },
+      "type": "object"
+    },
+    "message": {
+      "description": "Human-readable description of what went wrong.",
+      "type": "string"
+    }
+  },
+  "required": [
+    "code",
+    "message"
+  ],
+  "type": "object"
+}

Added value: +{
+  "description": "True when a character budget shortened at least one returned body. Absent when every returned article carries its full post-filter body. The per-article accounting is in `truncation`.",
+  "type": "boolean"
+}

Removed value: -[
-  "articles",
-  "totalReturned"
-]

Previous value: -"http://json-schema.org/draft-07/schema#"New value: +"https://json-schema.org/draft/2020-12/schema"

Added value: +false

Previous value: -"http://json-schema.org/draft-07/schema#"New value: +"https://json-schema.org/draft/2020-12/schema"

Added value: +[
+  {
+    "not": {
+      "required": [
+        "error"
+      ]
+    },
+    "required": [
+      "sourcePmid",
+      "relationship",
+      "offset",
+      "articles",
+      "totalCount",
+      "source"
+    ]
+  },
+  {
+    "required": [
+      "error"
+    ]
+  }
+]

Added value: +{
+  "additionalProperties": {},
+  "description": "Present when the call failed. Absent on success.",
+  "properties": {
+    "code": {
+      "description": "JSON-RPC error code for this failure.",
+      "maximum": 9007199254740991,
+      "minimum": -9007199254740991,
+      "type": "integer"
+    },
+    "data": {
+      "additionalProperties": {},
+      "properties": {
+        "reason": {
+          "description": "Machine-readable failure mode. Declared by this tool: `queue_full`: Local NCBI request queue is at capacity. `ncbi_unreachable`: NCBI E-utilities is unreachable after all retry attempts. `ncbi_deadline_exceeded`: Total request deadline expired before NCBI returned a response. `ncbi_invalid_response`: NCBI returned a body that could not be parsed (invalid XML/JSON). `ncbi_resource_not_found`: NCBI returned a structured \"not found\" error for the requested ID(s). `europepmc_unreachable`: Europe PMC was unreachable after all retry attempts. `europepmc_invalid_response`: Europe PMC returned a body that could not be parsed (invalid JSON or XML). `europepmc_invalid_input`: Europe PMC rejected the request input (empty query, unknown sort field, malformed parameter). `openalex_unreachable`: OpenAlex was unreachable after all retry attempts. `openalex_invalid_response`: OpenAlex returned a body that could not be parsed (invalid JSON). Other values are possible when a failure originates below the handler.",
+          "examples": [
+            "queue_full",
+            "ncbi_unreachable",
+            "ncbi_deadline_exceeded",
+            "ncbi_invalid_response",
+            "ncbi_resource_not_found",
+            "europepmc_unreachable",
+            "europepmc_invalid_response",
+            "europepmc_invalid_input",
+            "openalex_unreachable",
+            "openalex_invalid_response"
+          ],
+          "type": "string"
+        },
+        "recovery": {
+          "additionalProperties": {},
+          "description": "Actionable next step for the caller.",
+          "properties": {
+            "hint": {
+              "type": "string"
+            }
+          },
+          "required": [
+            "hint"
+          ],
+          "type": "object"
+        },
+        "retryable": {
+          "description": "Whether retrying may succeed.",
+          "type": "boolean"
+        }
+      },
+      "type": "object"
+    },
+    "message": {
+      "description": "Human-readable description of what went wrong.",
+      "type": "string"
+    }
+  },
+  "required": [
+    "code",
+    "message"
+  ],
+  "type": "object"
+}

Removed value: -[
-  "sourcePmid",
-  "relationship",
-  "offset",
-  "articles",
-  "totalCount",
-  "source"
-]

Previous value: -"http://json-schema.org/draft-07/schema#"New value: +"https://json-schema.org/draft/2020-12/schema"

Added value: +false

Previous value: -"http://json-schema.org/draft-07/schema#"New value: +"https://json-schema.org/draft/2020-12/schema"

Added value: +[
+  {
+    "not": {
+      "required": [
+        "error"
+      ]
+    },
+    "required": [
+      "citations",
+      "totalSubmitted",
+      "totalFormatted"
+    ]
+  },
+  {
+    "required": [
+      "error"
+    ]
+  }
+]

Added value: +{
+  "additionalProperties": {},
+  "description": "Present when the call failed. Absent on success.",
+  "properties": {
+    "code": {
+      "description": "JSON-RPC error code for this failure.",
+      "maximum": 9007199254740991,
+      "minimum": -9007199254740991,
+      "type": "integer"
+    },
+    "data": {
+      "additionalProperties": {},
+      "properties": {
+        "reason": {
+          "description": "Machine-readable failure mode. Declared by this tool: `queue_full`: Local NCBI request queue is at capacity. `ncbi_unreachable`: NCBI E-utilities is unreachable after all retry attempts. `ncbi_deadline_exceeded`: Total request deadline expired before NCBI returned a response. `ncbi_invalid_response`: NCBI returned a body that could not be parsed (invalid XML/JSON). `ncbi_resource_not_found`: NCBI returned a structured \"not found\" error for the requested ID(s). Other values are possible when a failure originates below the handler.",
+          "examples": [
+            "queue_full",
+            "ncbi_unreachable",
+            "ncbi_deadline_exceeded",
+            "ncbi_invalid_response",
+            "ncbi_resource_not_found"
+          ],
+          "type": "string"
+        },
+        "recovery": {
+          "additionalProperties": {},
+          "description": "Actionable next step for the caller.",
+          "properties": {
+            "hint": {
+              "type": "string"
+            }
+          },
+          "required": [
+            "hint"
+          ],
+          "type": "object"
+        },
+        "retryable": {
+          "description": "Whether retrying may succeed.",
+          "type": "boolean"
+        }
+      },
+      "type": "object"
+    },
+    "message": {
+      "description": "Human-readable description of what went wrong.",
+      "type": "string"
+    }
+  },
+  "required": [
+    "code",
+    "message"
+  ],
+  "type": "object"
+}

Removed value: -[
-  "citations",
-  "totalSubmitted",
-  "totalFormatted"
-]

Previous value: -"http://json-schema.org/draft-07/schema#"New value: +"https://json-schema.org/draft/2020-12/schema"

Added value: +false

Previous value: -"http://json-schema.org/draft-07/schema#"New value: +"https://json-schema.org/draft/2020-12/schema"

Added value: +[
+  {
+    "not": {
+      "required": [
+        "error"
+      ]
+    },
+    "required": [
+      "results",
+      "totalMatched",
+      "totalSubmitted",
+      "totalWarnings"
+    ]
+  },
+  {
+    "required": [
+      "error"
+    ]
+  }
+]

Added value: +{
+  "additionalProperties": {},
+  "description": "Present when the call failed. Absent on success.",
+  "properties": {
+    "code": {
+      "description": "JSON-RPC error code for this failure.",
+      "maximum": 9007199254740991,
+      "minimum": -9007199254740991,
+      "type": "integer"
+    },
+    "data": {
+      "additionalProperties": {},
+      "properties": {
+        "reason": {
+          "description": "Machine-readable failure mode. Declared by this tool: `queue_full`: Local NCBI request queue is at capacity. `ncbi_unreachable`: NCBI E-utilities is unreachable after all retry attempts. `ncbi_deadline_exceeded`: Total request deadline expired before NCBI returned a response. `ncbi_invalid_response`: NCBI returned a body that could not be parsed (invalid XML/JSON). `ncbi_resource_not_found`: NCBI returned a structured \"not found\" error for the requested ID(s). Other values are possible when a failure originates below the handler.",
+          "examples": [
+            "queue_full",
+            "ncbi_unreachable",
+            "ncbi_deadline_exceeded",
+            "ncbi_invalid_response",
+            "ncbi_resource_not_found"
+          ],
+          "type": "string"
+        },
+        "recovery": {
+          "additionalProperties": {},
+          "description": "Actionable next step for the caller.",
+          "properties": {
+            "hint": {
+              "type": "string"
+            }
+          },
+          "required": [
+            "hint"
+          ],
+          "type": "object"
+        },
+        "retryable": {
+          "description": "Whether retrying may succeed.",
+          "type": "boolean"
+        }
+      },
+      "type": "object"
+    },
+    "message": {
+      "description": "Human-readable description of what went wrong.",
+      "type": "string"
+    }
+  },
+  "required": [
+    "code",
+    "message"
+  ],
+  "type": "object"
+}

Removed value: -[
-  "results",
-  "totalMatched",
-  "totalSubmitted",
-  "totalWarnings"
-]

Previous value: -"http://json-schema.org/draft-07/schema#"New value: +"https://json-schema.org/draft/2020-12/schema"

Added value: +false

Previous value: -"http://json-schema.org/draft-07/schema#"New value: +"https://json-schema.org/draft/2020-12/schema"

Added value: +[
+  {
+    "not": {
+      "required": [
+        "error"
+      ]
+    },
+    "required": [
+      "query",
+      "offset",
+      "results",
+      "totalCount"
+    ]
+  },
+  {
+    "required": [
+      "error"
+    ]
+  }
+]

Added value: +{
+  "additionalProperties": {},
+  "description": "Present when the call failed. Absent on success.",
+  "properties": {
+    "code": {
+      "description": "JSON-RPC error code for this failure.",
+      "maximum": 9007199254740991,
+      "minimum": -9007199254740991,
+      "type": "integer"
+    },
+    "data": {
+      "additionalProperties": {},
+      "properties": {
+        "reason": {
+          "description": "Machine-readable failure mode. Declared by this tool: `queue_full`: Local NCBI request queue is at capacity. `ncbi_unreachable`: NCBI E-utilities is unreachable after all retry attempts. `ncbi_deadline_exceeded`: Total request deadline expired before NCBI returned a response. `ncbi_invalid_response`: NCBI returned a body that could not be parsed (invalid XML/JSON). `ncbi_resource_not_found`: NCBI returned a structured \"not found\" error for the requested ID(s). Other values are possible when a failure originates below the handler.",
+          "examples": [
+            "queue_full",
+            "ncbi_unreachable",
+            "ncbi_deadline_exceeded",
+            "ncbi_invalid_response",
+            "ncbi_resource_not_found"
+          ],
+          "type": "string"
+        },
+        "recovery": {
+          "additionalProperties": {},
+          "description": "Actionable next step for the caller.",
+          "properties": {
+            "hint": {
+              "type": "string"
+            }
+          },
+          "required": [
+            "hint"
+          ],
+          "type": "object"
+        },
+        "retryable": {
+          "description": "Whether retrying may succeed.",
+          "type": "boolean"
+        }
+      },
+      "type": "object"
+    },
+    "message": {
+      "description": "Human-readable description of what went wrong.",
+      "type": "string"
+    }
+  },
+  "required": [
+    "code",
+    "message"
+  ],
+  "type": "object"
+}

Removed value: -[
-  "query",
-  "offset",
-  "results",
-  "totalCount"
-]

Previous value: -"http://json-schema.org/draft-07/schema#"New value: +"https://json-schema.org/draft/2020-12/schema"

Added value: +false

Previous value: -"http://json-schema.org/draft-07/schema#"New value: +"https://json-schema.org/draft/2020-12/schema"

Added value: +[
+  {
+    "not": {
+      "required": [
+        "error"
+      ]
+    },
+    "required": [
+      "query",
+      "offset",
+      "pmids",
+      "summaries",
+      "searchUrl",
+      "effectiveQuery",
+      "totalCount",
+      "appliedFilters"
+    ]
+  },
+  {
+    "required": [
+      "error"
+    ]
+  }
+]

Added value: +{
+  "additionalProperties": {},
+  "description": "Present when the call failed. Absent on success.",
+  "properties": {
+    "code": {
+      "description": "JSON-RPC error code for this failure.",
+      "maximum": 9007199254740991,
+      "minimum": -9007199254740991,
+      "type": "integer"
+    },
+    "data": {
+      "additionalProperties": {},
+      "properties": {
+        "reason": {
+          "description": "Machine-readable failure mode. Declared by this tool: `queue_full`: Local NCBI request queue is at capacity. `ncbi_unreachable`: NCBI E-utilities is unreachable after all retry attempts. `ncbi_deadline_exceeded`: Total request deadline expired before NCBI returned a response. `ncbi_invalid_response`: NCBI returned a body that could not be parsed (invalid XML/JSON). `ncbi_resource_not_found`: NCBI returned a structured \"not found\" error for the requested ID(s). Other values are possible when a failure originates below the handler.",
+          "examples": [
+            "queue_full",
+            "ncbi_unreachable",
+            "ncbi_deadline_exceeded",
+            "ncbi_invalid_response",
+            "ncbi_resource_not_found"
+          ],
+          "type": "string"
+        },
+        "recovery": {
+          "additionalProperties": {},
+          "description": "Actionable next step for the caller.",
+          "properties": {
+            "hint": {
+              "type": "string"
+            }
+          },
+          "required": [
+            "hint"
+          ],
+          "type": "object"
+        },
+        "retryable": {
+          "description": "Whether retrying may succeed.",
+          "type": "boolean"
+        }
+      },
+      "type": "object"
+    },
+    "message": {
+      "description": "Human-readable description of what went wrong.",
+      "type": "string"
+    }
+  },
+  "required": [
+    "code",
+    "message"
+  ],
+  "type": "object"
+}

Removed value: -[
-  "query",
-  "offset",
-  "pmids",
-  "summaries",
-  "searchUrl",
-  "effectiveQuery",
-  "totalCount",
-  "appliedFilters"
-]

Previous value: -"http://json-schema.org/draft-07/schema#"New value: +"https://json-schema.org/draft/2020-12/schema"

Added value: +false

Previous value: -"http://json-schema.org/draft-07/schema#"New value: +"https://json-schema.org/draft/2020-12/schema"

Added value: +[
+  {
+    "not": {
+      "required": [
+        "error"
+      ]
+    },
+    "required": [
+      "original",
+      "corrected",
+      "hasSuggestion"
+    ]
+  },
+  {
+    "required": [
+      "error"
+    ]
+  }
+]

Added value: +{
+  "additionalProperties": {},
+  "description": "Present when the call failed. Absent on success.",
+  "properties": {
+    "code": {
+      "description": "JSON-RPC error code for this failure.",
+      "maximum": 9007199254740991,
+      "minimum": -9007199254740991,
+      "type": "integer"
+    },
+    "data": {
+      "additionalProperties": {},
+      "properties": {
+        "reason": {
+          "description": "Machine-readable failure mode. Declared by this tool: `queue_full`: Local NCBI request queue is at capacity. `ncbi_unreachable`: NCBI E-utilities is unreachable after all retry attempts. `ncbi_deadline_exceeded`: Total request deadline expired before NCBI returned a response. `ncbi_invalid_response`: NCBI returned a body that could not be parsed (invalid XML/JSON). `ncbi_resource_not_found`: NCBI returned a structured \"not found\" error for the requested ID(s). Other values are possible when a failure originates below the handler.",
+          "examples": [
+            "queue_full",
+            "ncbi_unreachable",
+            "ncbi_deadline_exceeded",
+            "ncbi_invalid_response",
+            "ncbi_resource_not_found"
+          ],
+          "type": "string"
+        },
+        "recovery": {
+          "additionalProperties": {},
+          "description": "Actionable next step for the caller.",
+          "properties": {
+            "hint": {
+              "type": "string"
+            }
+          },
+          "required": [
+            "hint"
+          ],
+          "type": "object"
+        },
+        "retryable": {
+          "description": "Whether retrying may succeed.",
+          "type": "boolean"
+        }
+      },
+      "type": "object"
+    },
+    "message": {
+      "description": "Human-readable description of what went wrong.",
+      "type": "string"
+    }
+  },
+  "required": [
+    "code",
+    "message"
+  ],
+  "type": "object"
+}

Removed value: -[
-  "original",
-  "corrected",
-  "hasSuggestion"
-]

Previous value: -"Digital Object Identifier; absent if no DOI is on record"New value: +"Digital Object Identifier, cased as the PMC ID Converter reports it; absent if no DOI is on record. DOIs are case-insensitive by spec and no case normalization is applied here, so casing can differ from a Europe PMC-sourced `doi` — compare the two case-insensitively."

Previous value: -"Europe PMC search query. Supports field tokens like `AUTH:\"<name>\"`, `JOURNAL:\"<title>\"`, `TITLE:\"<words>\"`, `PUB_YEAR:[2020 TO 2024]`, `DOI:\"...\"`, `EXT_ID:\"<pmid>\" AND SRC:MED`. Free text is matched broadly across abstract/title/keywords."New value: +"Europe PMC search query. Supports field tokens like `AUTH:\"<name>\"`, `JOURNAL:\"<title>\"`, `TITLE:\"<words>\"`, `PUB_YEAR:[2020 TO 2024]`, `DOI:\"...\"`, `EXT_ID:<pmid> AND SRC:MED`, `PMCID:PMC<digits>`. Identifier tokens combined with `AND SRC:` must be unquoted — the quoted form matches nothing. Free text is matched broadly across abstract/title/keywords."

Previous value: -"First few hundred characters of the abstract as display-ready plain text — JATS/HTML markup stripped and HTML entities decoded — when `resultType: \"core\"` is requested"New value: +"First 400 characters of the abstract as display-ready plain text — JATS/HTML markup stripped and HTML entities decoded — when `resultType: \"core\"` is requested, with a trailing … appended when the abstract was cut. Check `abstractTruncated` before treating it as the whole abstract."

Added value: +{
+  "description": "Whether `abstractSnippet` was cut short of the full abstract. Retrieve the complete text with `pubmed_europepmc_fetch` using this record’s `source` and `epmcId`. Present whenever `abstractSnippet` is; omitted when Europe PMC carries no abstract.",
+  "type": "boolean"
+}

Previous value: -"DOI when present"New value: +"DOI when present, cased as Europe PMC reports it. DOIs are case-insensitive by spec and no case normalization is applied here, so the same DOI can arrive in a different case from `pubmed_fetch_articles` (Europe PMC `10.1056/nejmoa2212948`, NCBI `10.1056/NEJMoa2212948`) — a byte-for-byte comparison across the two reports a false mismatch."

Previous value: -"Europe PMC's internal record id; key for `fullTextXML` lookup"New value: +"Europe PMC's internal record id. Pass it with this hit's `source` to `pubmed_europepmc_fetch` for the complete record. Europe PMC's `fullTextXML` is keyed on `pmcId`, not on this id, so records without a PMC counterpart have no full text to fetch."

Previous value: -"DOI"New value: +"DOI, cased as NCBI reports it (usually the publisher's mixed case). DOIs are case-insensitive by spec and no case normalization is applied here, so the same DOI can arrive in a different case from `pubmed_europepmc_search` and `pubmed_europepmc_fetch` (NCBI `10.1056/NEJMoa2212948`, Europe PMC `10.1056/nejmoa2212948`) — a byte-for-byte comparison across the two reports a false mismatch."

Added value: +{
+  "description": "Per-article budget for body text, in characters. Counts `source=pmc` section and subsection text, or the `source=unpaywall` `content` body; titles, abstracts, identifiers, and references are never counted or shortened. Applied after `sections`, `maxSections`, and `includeReferences`, so semantic filtering is unaffected. The response-wide ceiling is this value times the number of articles returned. Omit for the full body.",
+  "maximum": 1000000,
+  "minimum": 1,
+  "type": "integer"
+}

Added value: +{
+  "description": "Budget for a single top-level body section, in characters, counting the section text plus its subsections. Combine with `maxCharacters` to cap both one section and the article; the tighter of the two wins. Applies to `source=pmc` results only.",
+  "maximum": 1000000,
+  "minimum": 1,
+  "type": "integer"
+}

Added value: +{
+  "default": "truncate",
+  "description": "How to spend `maxCharacters` across an article that exceeds it. truncate: fill sections in document order, so early sections stay whole and sections past the budget are dropped (counted in `truncation.omittedSections`). outline: split the budget evenly so every section keeps its heading, and an excerpt as far as the budget reaches — use it to survey what an article contains before requesting specific `sections`. Ignored when no budget is set, and identical for `source=unpaywall` bodies, which have no headings to preserve.",
+  "enum": [
+    "truncate",
+    "outline"
+  ],
+  "type": "string"
+}

Previous value: -"PMC IDs to fetch (e.g. [\"PMC9575052\"]). Provide exactly one of `pmcids`, `pmids`, or `dois`."New value: +"PMC IDs to fetch (e.g. [\"PMC9575052\"]). Provide exactly one of `pmcids`, `pmids`, or `dois`. PMC IDs with no retrievable full text fall through to Europe PMC, then to Unpaywall on the DOI the chain resolves for them."

Previous value: -[
-  {
-    "additionalProperties": false,
-    "description": "Structured JATS full-text article. `viaSource` records whether the JATS came from NCBI PMC or Europe PMC.",
-    "properties": {
-      "abstract": {
-        "description": "Abstract",
-        "type": "string"
-      },
-      "affiliations": {
-        "description": "Author affiliations",
-        "items": {
-          "type": "string"
-        },
-        "type": "array"
-      },
-      "articleType": {
-        "description": "Article type",
-        "type": "string"
-      },
-      "authors": {
-        "description": "Authors",
-        "items": {
-          "additionalProperties": false,
-          "description": "Author entry",
-          "properties": {
-            "collectiveName": {
-              "description": "Group name",
-              "type": "string"
-            },
-            "givenNames": {
-              "description": "Given names",
-              "type": "string"
-            },
-            "lastName": {
-              "description": "Last name",
-              "type": "string"
-            }
-          },
-          "type": "object"
-        },
-        "type": "array"
-      },
-      "doi": {
-        "description": "DOI",
-        "type": "string"
-      },
-      "epmcId": {
-        "description": "Europe PMC record id — present when `viaSource` is `europepmc`",
-        "type": "string"
-      },
-      "epmcSource": {
-        "description": "Europe PMC source code when `viaSource` is `europepmc`. Common values: `MED` (PubMed-derived), `PMC` (PMC counterpart), `PPR` (preprint), `PAT` (patent), `AGR` (Agricola), plus less common codes (`CTX`, `CBA`, `ETH`, `HIR`). Treat as opaque — EPMC may introduce new codes.",
-        "type": "string"
-      },
-      "journal": {
-        "additionalProperties": false,
-        "description": "Journal information",
-        "properties": {
-          "issn": {
-            "description": "ISSN",
-            "type": "string"
-          },
-          "issue": {
-            "description": "Issue number",
-            "type": "string"
-          },
-          "pages": {
-            "description": "Page range",
-            "type": "string"
-          },
-          "title": {
-            "description": "Journal title",
-            "type": "string"
-          },
-          "volume": {
-            "description": "Volume number",
-            "type": "string"
-          }
-        },
-        "type": "object"
-      },
-      "keywords": {
-        "description": "Keywords",
-        "items": {
-          "type": "string"
-        },
-        "type": "array"
-      },
-      "pmcId": {
-        "description": "PMC ID — present for NCBI PMC records and Europe PMC entries that have a PMC counterpart. Absent for EPMC-only records like preprints; use `epmcId` in that case.",
-        "type": "string"
-      },
-      "pmcUrl": {
-        "description": "PMC URL — derived from `pmcId` when present",
-        "type": "string"
-      },
-      "pmid": {
-        "description": "PubMed ID",
-        "type": "string"
-      },
-      "publicationDate": {
-        "additionalProperties": false,
-        "description": "Publication date",
-        "properties": {
-          "day": {
-            "description": "Publication day",
-            "type": "string"
-          },
-          "month": {
-            "description": "Publication month",
-            "type": "string"
-          },
-          "year": {
-            "description": "Publication year",
-            "type": "string"
-          }
-        },
-        "type": "object"
-      },
-      "pubmedUrl": {
-        "description": "PubMed URL",
-        "type": "string"
-      },
-      "references": {
-        "description": "Reference list",
-        "items": {
-          "additionalProperties": false,
-          "description": "Reference entry",
-          "properties": {
-            "citation": {
-              "description": "Citation text",
-              "type": "string"
-            },
-            "id": {
-              "description": "Reference ID",
-              "type": "string"
-            },
-            "label": {
-              "description": "Reference label",
-              "type": "string"
-            }
-          },
-          "required": [
-            "citation"
-          ],
-          "type": "object"
-        },
-        "type": "array"
-      },
-      "sections": {
-        "description": "Article body sections",
-        "items": {
-          "additionalProperties": false,
-          "description": "Article body section",
-          "properties": {
-            "label": {
-              "description": "Section label",
-              "type": "string"
-            },
-            "subsections": {
-              "description": "Nested subsections",
-              "items": {
-                "additionalProperties": false,
-                "description": "Article subsection",
-                "properties": {
-                  "label": {
-                    "description": "Subsection label",
-                    "type": "string"
-                  },
-                  "text": {
-                    "description": "Subsection body text",
-                    "type": "string"
-                  },
-                  "title": {
-                    "description": "Subsection heading",
-                    "type": "string"
-                  }
-                },
-                "required": [
-                  "text"
-                ],
-                "type": "object"
-              },
-              "type": "array"
-            },
-            "text": {
-              "description": "Section body text",
-              "type": "string"
-            },
-            "title": {
-              "description": "Section heading",
-              "type": "string"
-            }
-          },
-          "required": [
-            "text"
-          ],
-          "type": "object"
-        },
-        "type": "array"
-      },
-      "source": {
-        "const": "pmc",
-        "description": "Structured JATS — same DTD whether sourced from NCBI PMC or Europe PMC",
-        "type": "string"
-      },
-      "title": {
-        "description": "Article title",
-        "type": "string"
-      },
-      "viaSource": {
-        "description": "Which layer produced the JATS: `pmc` for NCBI PMC EFetch (db=pmc), `europepmc` for Europe PMC `fullTextXML`. Both paths return the same JATS shape; the discriminator records origin for observability and license attribution.",
-        "enum": [
-          "pmc",
-          "europepmc"
-        ],
-        "type": "string"
-      }
-    },
-    "required": [
-      "source",
-      "viaSource",
-      "sections"
-    ],
-    "type": "object"
-  },
-  {
-    "additionalProperties": false,
-    "description": "Best-effort full text from an open-access copy",
-    "properties": {
-      "content": {
-        "description": "Full article text — Markdown or plain text per `contentFormat`",
-        "type": "string"
-      },
-      "contentFormat": {
-        "description": "How `content` was extracted. html-markdown: Defuddle extracted Markdown from an HTML landing page; light section structure may survive but is not guaranteed. pdf-text: unpdf extracted plain text from a PDF; no section, reference, or heading structure.",
-        "enum": [
-          "html-markdown",
-          "pdf-text"
-        ],
-        "type": "string"
-      },
-      "doi": {
-        "description": "DOI used to locate the open-access copy",
-        "type": "string"
-      },
-      "hostType": {
-        "description": "`publisher` or `repository` — where the OA copy is hosted",
-        "type": "string"
-      },
-      "license": {
-        "description": "License identifier from Unpaywall (e.g. cc-by, cc0)",
-        "type": "string"
-      },
-      "pmid": {
-        "description": "PubMed ID when input was `pmids`; absent for `dois` input",
-        "type": "string"
-      },
-      "pubmedUrl": {
-        "description": "PubMed URL — present when `pmid` is set",
-        "type": "string"
-      },
-      "source": {
-        "const": "unpaywall",
-        "description": "Content fetched from an open-access copy indexed by Unpaywall. Best-effort — structural fidelity depends on `contentFormat`.",
-        "type": "string"
-      },
-      "sourceUrl": {
-        "description": "URL the content was fetched from",
-        "type": "string"
-      },
-      "title": {
-        "description": "Detected article title when present",
-        "type": "string"
-      },
-      "totalPages": {
-        "description": "Page count reported by the PDF extractor; absent for HTML",
-        "type": "number"
-      },
-      "version": {
-        "description": "OA version: submittedVersion | acceptedVersion | publishedVersion",
-        "type": "string"
-      },
-      "viaSource": {
-        "const": "unpaywall",
-        "description": "Layer that produced this article. Constant `unpaywall` for this branch.",
-        "type": "string"
-      },
-      "wordCount": {
-        "description": "Approximate word count reported by the HTML extractor; absent for PDFs",
-        "type": "number"
-      }
-    },
-    "required": [
-      "source",
-      "viaSource",
-      "contentFormat",
-      "doi",
-      "sourceUrl",
-      "content"
-    ],
-    "type": "object"
-  }
-]New value: +[
+  {
+    "additionalProperties": false,
+    "description": "Structured JATS full-text article. `viaSource` records whether the JATS came from NCBI PMC or Europe PMC.",
+    "properties": {
+      "abstract": {
+        "description": "Abstract",
+        "type": "string"
+      },
+      "affiliations": {
+        "description": "Author affiliations",
+        "items": {
+          "type": "string"
+        },
+        "type": "array"
+      },
+      "articleType": {
+        "description": "Article type",
+        "type": "string"
+      },
+      "authors": {
+        "description": "Authors",
+        "items": {
+          "additionalProperties": false,
+          "description": "Author entry",
+          "properties": {
+            "collectiveName": {
+              "description": "Group name",
+              "type": "string"
+            },
+            "givenNames": {
+              "description": "Given names",
+              "type": "string"
+            },
+            "lastName": {
+              "description": "Last name",
+              "type": "string"
+            }
+          },
+          "type": "object"
+        },
+        "type": "array"
+      },
+      "doi": {
+        "description": "DOI, cased as the tier that served this record reports it (NCBI PMC, Europe PMC, or Unpaywall). DOIs are case-insensitive by spec and no case normalization is applied here, so casing can differ between tiers and from other tools — compare case-insensitively.",
+        "type": "string"
+      },
+      "epmcId": {
+        "description": "Europe PMC record id — present when `viaSource` is `europepmc`",
+        "type": "string"
+      },
+      "epmcSource": {
+        "description": "Europe PMC source code when `viaSource` is `europepmc`. Common values: `MED` (PubMed-derived), `PMC` (PMC counterpart), `PPR` (preprint), `PAT` (patent), `AGR` (Agricola), plus less common codes (`CTX`, `CBA`, `ETH`, `HIR`). Treat as opaque — EPMC may introduce new codes.",
+        "type": "string"
+      },
+      "journal": {
+        "additionalProperties": false,
+        "description": "Journal information",
+        "properties": {
+          "issn": {
+            "description": "ISSN",
+            "type": "string"
+          },
+          "issue": {
+            "description": "Issue number",
+            "type": "string"
+          },
+          "pages": {
+            "description": "Page range",
+            "type": "string"
+          },
+          "title": {
+            "description": "Journal title",
+            "type": "string"
+          },
+          "volume": {
+            "description": "Volume number",
+            "type": "string"
+          }
+        },
+        "type": "object"
+      },
+      "keywords": {
+        "description": "Keywords",
+        "items": {
+          "type": "string"
+        },
+        "type": "array"
+      },
+      "pmcId": {
+        "description": "PMC ID — present for NCBI PMC records and Europe PMC entries that have a PMC counterpart. Absent for EPMC-only records like preprints; use `epmcId` in that case.",
+        "type": "string"
+      },
+      "pmcUrl": {
+        "description": "PMC URL — derived from `pmcId` when present",
+        "type": "string"
+      },
+      "pmid": {
+        "description": "PubMed ID",
+        "type": "string"
+      },
+      "publicationDate": {
+        "additionalProperties": false,
+        "description": "Publication date",
+        "properties": {
+          "day": {
+            "description": "Publication day",
+            "type": "string"
+          },
+          "month": {
+            "description": "Publication month",
+            "type": "string"
+          },
+          "year": {
+            "description": "Publication year",
+            "type": "string"
+          }
+        },
+        "type": "object"
+      },
+      "pubmedUrl": {
+        "description": "PubMed URL",
+        "type": "string"
+      },
+      "references": {
+        "description": "Reference list",
+        "items": {
+          "additionalProperties": false,
+          "description": "Reference entry",
+          "properties": {
+            "citation": {
+              "description": "Citation text",
+              "type": "string"
+            },
+            "id": {
+              "description": "Reference ID",
+              "type": "string"
+            },
+            "label": {
+              "description": "Reference label",
+              "type": "string"
+            }
+          },
+          "required": [
+            "citation"
+          ],
+          "type": "object"
+        },
+        "type": "array"
+      },
+      "sections": {
+        "description": "Article body sections",
+        "items": {
+          "additionalProperties": false,
+          "description": "Article body section",
+          "properties": {
+            "label": {
+              "description": "Section label",
+              "type": "string"
+            },
+            "subsections": {
+              "description": "Nested subsections",
+              "items": {
+                "additionalProperties": false,
+                "description": "Article subsection",
+                "properties": {
+                  "label": {
+                    "description": "Subsection label",
+                    "type": "string"
+                  },
+                  "text": {
+                    "description": "Subsection body text",
+                    "type": "string"
+                  },
+                  "title": {
+                    "description": "Subsection heading",
+                    "type": "string"
+                  }
+                },
+                "required": [
+                  "text"
+                ],
+                "type": "object"
+              },
+              "type": "array"
+            },
+            "text": {
+              "description": "Section body text",
+              "type": "string"
+            },
+            "title": {
+              "description": "Section heading",
+              "type": "string"
+            }
+          },
+          "required": [
+            "text"
+          ],
+          "type": "object"
+        },
+        "type": "array"
+      },
+      "source": {
+        "const": "pmc",
+        "description": "Structured JATS — same DTD whether sourced from NCBI PMC or Europe PMC",
+        "type": "string"
+      },
+      "title": {
+        "description": "Article title",
+        "type": "string"
+      },
+      "viaSource": {
+        "description": "Which layer produced the JATS: `pmc` for NCBI PMC EFetch (db=pmc), `europepmc` for Europe PMC `fullTextXML`. Both paths return the same JATS shape; the discriminator records origin for observability and license attribution.",
+        "enum": [
+          "pmc",
+          "europepmc"
+        ],
+        "type": "string"
+      }
+    },
+    "required": [
+      "source",
+      "viaSource",
+      "sections"
+    ],
+    "type": "object"
+  },
+  {
+    "additionalProperties": false,
+    "description": "Best-effort full text from an open-access copy",
+    "properties": {
+      "content": {
+        "description": "Full article text — Markdown or plain text per `contentFormat`",
+        "type": "string"
+      },
+      "contentFormat": {
+        "description": "How `content` was extracted. html-markdown: Defuddle extracted Markdown from an HTML landing page; light section structure may survive but is not guaranteed. pdf-text: unpdf extracted plain text from a PDF; no section, reference, or heading structure.",
+        "enum": [
+          "html-markdown",
+          "pdf-text"
+        ],
+        "type": "string"
+      },
+      "doi": {
+        "description": "DOI used to locate the open-access copy",
+        "type": "string"
+      },
+      "hostType": {
+        "description": "`publisher` or `repository` — where the OA copy is hosted",
+        "type": "string"
+      },
+      "license": {
+        "description": "License identifier from Unpaywall (e.g. cc-by, cc0)",
+        "type": "string"
+      },
+      "pmcId": {
+        "description": "PMC ID this article was requested under, in `PMC<digits>` form — present for `pmcids` input, absent for `pmids` and `dois` input. Ties the article back to the requested identifier, which `unavailable[]` keys on for the ids that found nothing.",
+        "type": "string"
+      },
+      "pmid": {
+        "description": "PubMed ID when input was `pmids`; absent for `pmcids` and `dois` input",
+        "type": "string"
+      },
+      "pubmedUrl": {
+        "description": "PubMed URL — present when `pmid` is set",
+        "type": "string"
+      },
+      "source": {
+        "const": "unpaywall",
+        "description": "Content fetched from an open-access copy indexed by Unpaywall. Best-effort — structural fidelity depends on `contentFormat`.",
+        "type": "string"
+      },
+      "sourceUrl": {
+        "description": "URL the content was fetched from",
+        "type": "string"
+      },
+      "title": {
+        "description": "Detected article title when present",
+        "type": "string"
+      },
+      "totalPages": {
+        "description": "Page count reported by the PDF extractor; absent for HTML",
+        "type": "number"
+      },
+      "version": {
+        "description": "OA version: submittedVersion | acceptedVersion | publishedVersion",
+        "type": "string"
+      },
+      "viaSource": {
+        "const": "unpaywall",
+        "description": "Layer that produced this article. Constant `unpaywall` for this branch.",
+        "type": "string"
+      },
+      "wordCount": {
+        "description": "Approximate word count reported by the HTML extractor; absent for PDFs",
+        "type": "number"
+      }
+    },
+    "required": [
+      "source",
+      "viaSource",
+      "contentFormat",
+      "doi",
+      "sourceUrl",
+      "content"
+    ],
+    "type": "object"
+  }
+]

Previous value: -"Optional guidance when a `sections` filter removed every body section — names the requested section terms and the affected article id(s), and suggests retrying without `sections` or using broader headings. Absent when no section filter was applied or sections matched."New value: +"Optional guidance for a partial or empty body. A `sections`-filter miss names the requested terms and affected article id(s) and suggests retrying without `sections` or using broader headings. A metadata-only record names the id(s) the chain could retrieve as front matter only and points at `pubmed_fetch_articles` for the abstract. A budgeted response names the characters returned versus carried and points at `truncation`. Absent when none of those applies."

Added value: +{
+  "additionalProperties": false,
+  "description": "Character accounting for full text the budget shortened. Present only when a budget actually removed characters — its absence means every returned article carries its full post-filter body.",
+  "properties": {
+    "articles": {
+      "description": "Per-article accounting, covering only the articles the budget shortened",
+      "items": {
+        "additionalProperties": false,
+        "description": "Character accounting for one article the budget shortened",
+        "properties": {
+          "id": {
+            "description": "Identifier for the article — PMCID, PMID, DOI, or Europe PMC id, whichever the article carries first",
+            "type": "string"
+          },
+          "originalCharacters": {
+            "description": "Body characters this article carried before the budget pass",
+            "type": "number"
+          },
+          "returnedCharacters": {
+            "description": "Body characters this article carries in the response",
+            "type": "number"
+          },
+          "sections": {
+            "description": "Per-section accounting for `source: pmc` articles, in document order, including sections dropped for budget. Absent for `source: unpaywall`, whose body has no section structure.",
+            "items": {
+              "additionalProperties": false,
+              "description": "Character accounting for one body section of a budgeted article",
+              "properties": {
+                "originalCharacters": {
+                  "description": "Body characters this section carried before the budget pass",
+                  "type": "number"
+                },
+                "returnedCharacters": {
+                  "description": "Body characters this section carries in the response. Zero means the section was dropped in `truncate` mode, or kept as a heading-only entry in `outline` mode.",
+                  "type": "number"
+                },
+                "title": {
+                  "description": "Section heading, when the section carries one",
+                  "type": "string"
+                },
+                "truncated": {
+                  "description": "True when the section returned fewer characters than it originally carried",
+                  "type": "boolean"
+                }
+              },
+              "required": [
+                "originalCharacters",
+                "returnedCharacters",
+                "truncated"
+              ],
+              "type": "object"
+            },
+            "type": "array"
+          },
+          "source": {
+            "description": "Which output shape was budgeted: `pmc` budgets body sections and subsections, `unpaywall` budgets the single `content` body",
+            "enum": [
+              "pmc",
+              "unpaywall"
+            ],
+            "type": "string"
+          }
+        },
+        "required": [
+          "id",
+          "source",
+          "originalCharacters",
+          "returnedCharacters"
+        ],
+        "type": "object"
+      },
+      "type": "array"
+    },
+    "maxCharacters": {
+      "description": "The `maxCharacters` budget applied, when set",
+      "type": "number"
+    },
+    "maxCharactersPerSection": {
+      "description": "The `maxCharactersPerSection` budget applied, when set",
+      "type": "number"
+    },
+    "mode": {
+      "description": "The `overflowMode` that produced these results",
+      "enum": [
+        "truncate",
+        "outline"
+      ],
+      "type": "string"
+    },
+    "omittedSections": {
+      "description": "Body sections dropped entirely because an article budget was exhausted before reaching them. Always 0 in `outline` mode, which keeps every heading.",
+      "type": "number"
+    },
+    "originalCharacters": {
+      "description": "Body characters the shortened articles carried before the budget pass",
+      "type": "number"
+    },
+    "returnedCharacters": {
+      "description": "Body characters the shortened articles carry in this response",
+      "type": "number"
+    }
+  },
+  "required": [
+    "mode",
+    "originalCharacters",
+    "returnedCharacters",
+    "omittedSections",
+    "articles"
+  ],
+  "type": "object"
+}

Previous value: -"Why no full text was returned. not-found: upstream returned no record for this ID. no-pmc-fallback-disabled: every tier was skipped (`triedTiers` is all `not-attempted`) — typically because EPMC (`EUROPEPMC_ENABLED`) and Unpaywall (`UNPAYWALL_EMAIL`) are not configured. no-epmc-fulltext: EPMC indexed the record but publishes no fullTextXML. no-doi: no DOI to query Unpaywall. no-oa: Unpaywall has no OA copy. fetch-failed: download failed. parse-failed: extraction empty. service-error: upstream server failure (threw, timed out, or returned malformed data)."New value: +"Why no full text was returned. not-found: upstream returned no record for this ID. no-pmc-fallback-disabled: every tier was skipped (`triedTiers` is all `not-attempted`) — typically because EPMC (`EUROPEPMC_ENABLED`) and Unpaywall (`UNPAYWALL_EMAIL`) are not configured. no-epmc-fulltext: EPMC indexed the record but publishes no fullTextXML. no-body: the record was retrieved but carries front matter and abstract only, with no body sections — use `pubmed_fetch_articles` for the metadata. no-doi: no DOI to query Unpaywall. no-oa: Unpaywall has no OA copy. fetch-failed: download failed. parse-failed: extraction empty. service-error: upstream server failure (threw, timed out, or returned malformed data)."

Previous value: -[
-  "not-found",
-  "no-pmc-fallback-disabled",
-  "no-epmc-fulltext",
-  "no-doi",
-  "no-oa",
-  "fetch-failed",
-  "parse-failed",
-  "service-error"
-]New value: +[
+  "not-found",
+  "no-pmc-fallback-disabled",
+  "no-epmc-fulltext",
+  "no-body",
+  "no-doi",
+  "no-oa",
+  "fetch-failed",
+  "parse-failed",
+  "service-error"
+]

Previous value: -"Per-tier outcome. not-attempted: tier was skipped. miss: tier returned no record. no-fulltext: EPMC indexed the record but publishes no fullTextXML. no-doi: no DOI to query Unpaywall. no-oa: Unpaywall reports no open-access copy. fetch-failed: OA copy download failed. parse-failed: extraction produced empty content. service-error: tier service threw."New value: +"Per-tier outcome. not-attempted: tier was skipped. miss: tier returned no record. no-fulltext: EPMC indexed the record but publishes no fullTextXML. no-body: the tier returned a record with front matter and abstract but no body sections, so the chain continued. no-doi: no DOI to query Unpaywall. no-oa: Unpaywall reports no open-access copy. fetch-failed: OA copy download failed. parse-failed: extraction produced empty content. service-error: tier service threw."

Previous value: -[
-  "not-attempted",
-  "miss",
-  "no-fulltext",
-  "no-doi",
-  "no-oa",
-  "fetch-failed",
-  "parse-failed",
-  "service-error"
-]New value: +[
+  "not-attempted",
+  "miss",
+  "no-fulltext",
+  "no-body",
+  "no-doi",
+  "no-oa",
+  "fetch-failed",
+  "parse-failed",
+  "service-error"
+]

Added value: +{
+  "default": 0,
+  "description": "Result offset for pagination (0-based). Pass the `nextOffset` from the previous response to get the following page; the exact-descriptor match is pinned to the first page only.",
+  "maximum": 9007199254740991,
+  "minimum": 0,
+  "type": "integer"
+}

Added value: +{
+  "description": "Offset to request for the next page. Omitted when this is the last page, so its absence is the end-of-results signal.",
+  "type": "number"
+}

Previous value: -"Optional guidance when no descriptors matched — suggests spell-check or free-text search. Absent on successful results."New value: +"Optional guidance when no descriptors matched or the offset overshot the result set — suggests spell-check, free-text search, or resetting the offset. Absent on successful result pages."

Added value: +{
+  "description": "Result offset this page was read from",
+  "type": "number"
+}

Previous value: -"Total matching MeSH descriptors"New value: +"Total MeSH descriptors matching the query upstream, before the maxResults cap"

Previous value: -[
-  "query",
-  "results",
-  "totalCount"
-]New value: +[
+  "query",
+  "offset",
+  "results",
+  "totalCount"
+]

Previous value: -"Result offset for pagination (0-based)"New value: +"Result offset for pagination (0-based). PubMed serves at most the first 9999 records of a result set, so this caps at 9998; narrow the query or add filters to reach anything beyond it."

Previous value: -9007199254740991New value: +9998

Previous value: -"Fetch brief summaries for top N results (0 = PMIDs only)"New value: +"Fetch brief summaries for top N results (0 = PMIDs only). Above the 50 cap, pass the remaining PMIDs to pubmed_fetch_articles."

Previous value: -"Optional guidance when results are empty or paging overshot — e.g. how to broaden filters or reset offset. Absent on successful result pages."New value: +"Optional guidance when the result set does not reflect what was asked for — a field tag PubMed ignored, a phrase it matched nothing for, a dateRange dropped for having one bound, no matches at all, or paging past the end. Absent when nothing applies."

Previous value: -"DOI"New value: +"DOI, cased as NCBI reports it. DOIs are case-insensitive by spec and no case normalization is applied here, so casing can differ from a Europe PMC-sourced `doi` — compare the two case-insensitively."

Added value: +{
+  "description": "Optional guidance when a `sections` filter removed every body section — names the requested section terms and the affected article id(s), and suggests retrying without `sections` or using broader headings. Absent when no section filter was applied or sections matched.",
+  "type": "string"
+}

Previous value: -"Article identifiers to convert. All IDs must be the same type. DOIs: \"10.1093/nar/gks1195\", PMIDs: \"23193287\", PMCIDs: \"PMC3531190\"."New value: +"Article identifiers to convert. All IDs must be the same type. DOIs: \"10.1093/nar/gks1195\", PMIDs: \"23193287\", PMCIDs: \"PMC3531190\" (the \"PMC\" prefix is optional — bare digits like \"3531190\" are also accepted)."

Previous value: -"First few hundred characters of the abstract when `resultType: \"core\"` is requested"New value: +"First few hundred characters of the abstract as display-ready plain text — JATS/HTML markup stripped and HTML entities decoded — when `resultType: \"core\"` is requested"

Added value: +{
+  "description": "NCBI Entrez UID for this record — the join key for E-utilities (eSummary/eFetch db=mesh).",
+  "type": "string"
+}

Previous value: -"MeSH descriptor unique identifier"New value: +"Canonical MeSH DescriptorUI (e.g. \"D003924\") — resolves at the MeSH Browser and NLM linked data. Falls back to the raw Entrez UID when a record is not decodable."

Previous value: -"MeSH tree numbers"New value: +"Navigable MeSH tree numbers (e.g. \"D02.078.370.141.450\"). Omitted for supplementary concept records (SCRs), which map to a heading rather than occupying a tree position."

Previous value: -[
-  "meshId",
-  "name"
-]New value: +[
+  "meshId",
+  "entrezUid",
+  "name"
+]

Removed value: -{
-  "description": "Total matching records across all pages",
-  "type": "number"
-}

Added value: +{
+  "description": "Total matching records across all pages",
+  "type": "number"
+}

Previous value: -[
-  "hits",
-  "cursorMark",
-  "searchUrl",
-  "query",
-  "hitCount",
-  "appliedSources"
-]New value: +[
+  "hits",
+  "cursorMark",
+  "searchUrl",
+  "query",
+  "totalCount",
+  "appliedSources"
+]

Added value: +{
+  "description": "Total related articles found before windowing",
+  "type": "number"
+}

Removed value: -{
-  "description": "Total related articles found before windowing",
-  "type": "number"
-}

Previous value: -[
-  "sourcePmid",
-  "relationship",
-  "offset",
-  "articles",
-  "totalFound",
-  "source"
-]New value: +[
+  "sourcePmid",
+  "relationship",
+  "offset",
+  "articles",
+  "totalCount",
+  "source"
+]

Added value: +{
+  "description": "Total matching MeSH descriptors",
+  "type": "number"
+}

Previous value: -[
-  "query",
-  "results"
-]New value: +[
+  "query",
+  "results",
+  "totalCount"
+]

Added value: +{
+  "description": "Total matching articles",
+  "type": "number"
+}

Removed value: -{
-  "description": "Total matching articles",
-  "type": "number"
-}

Previous value: -[
-  "query",
-  "offset",
-  "pmids",
-  "summaries",
-  "searchUrl",
-  "effectiveQuery",
-  "totalFound",
-  "appliedFilters"
-]New value: +[
+  "query",
+  "offset",
+  "pmids",
+  "summaries",
+  "searchUrl",
+  "effectiveQuery",
+  "totalCount",
+  "appliedFilters"
+]

Previous value: -"Optional EPMC sort: `<field> asc|desc`. Documented sortable fields: `P_PDATE_D` (publication date), `CITED` (citation count), `AUTH_FIRST` (first author surname), `PUB_YEAR` (publication year). Examples: `P_PDATE_D desc` (newest first), `CITED desc` (most cited). Omit for relevance ranking. Fields outside the documented set are rejected by EPMC."New value: +"Optional EPMC sort: `<field> asc|desc`. Documented sortable fields: `P_PDATE_D` (publication date), `CITED` (citation count), `AUTH_FIRST` (first author surname), `PUB_YEAR` (publication year). Examples: `P_PDATE_D desc` (newest first), `CITED desc` (most cited). Omit for relevance ranking. Fields outside the documented set are rejected by EPMC. Note: `P_PDATE_D` is ignored for preprint-only (`sources: [\"PPR\"]`) result sets — preprints have no populated publication date, so use `PUB_YEAR` to order preprints by date."

Added value: +{
+  "description": "Optional guidance when no articles were returned — points to discovery tools. Absent on successful fetches.",
+  "type": "string"
+}

Previous value: -"DOIs to resolve (e.g. [\"10.21203/rs.3.rs-9010375/v1\"]). Provide exactly one of `pmcids`, `pmids`, or `dois`. Covers preprints and EPMC-only OA records that lack PMID/PMCID. Chain: Europe PMC search-by-DOI → fullTextXML → Unpaywall."New value: +"DOIs to resolve (e.g. [\"10.21203/rs.3.rs-9010375/v1\"]). Provide exactly one of `pmcids`, `pmids`, or `dois`. Resolved to a PMCID via the PMC ID Converter and returned as structured JATS when the article is in PMC; DOIs with no PMC counterpart (preprints, EPMC-only OA) fall through to Europe PMC, then Unpaywall, when those layers are enabled."

Added value: +{
+  "default": 0,
+  "description": "Result offset for pagination (0-based); page through results by incrementing by maxResults",
+  "maximum": 9007199254740991,
+  "minimum": 0,
+  "type": "integer"
+}

Previous value: -"Optional guidance when results are empty — e.g. invalid source PMID, or references requested for a non-PMC source. Absent on successful result pages."New value: +"Guidance when results are empty, a fallback provider answered, or offset overshot. Absent on a clean NCBI result page."

Added value: +{
+  "description": "Result offset used",
+  "type": "number"
+}

Added value: +{
+  "description": "Provider that answered this request",
+  "enum": [
+    "ncbi",
+    "europepmc",
+    "openalex"
+  ],
+  "type": "string"
+}

Previous value: -"Total related articles found before truncation"New value: +"Total related articles found before windowing"

Previous value: -[
-  "sourcePmid",
-  "relationship",
-  "articles",
-  "totalFound"
-]New value: +[
+  "sourcePmid",
+  "relationship",
+  "offset",
+  "articles",
+  "totalFound",
+  "source"
+]

Previous value: -[
-  {
-    "description": "Single citation style. One of: apa, mla, bibtex, ris.",
-    "enum": [
-      "apa",
-      "mla",
-      "bibtex",
-      "ris"
-    ],
-    "type": "string"
-  },
-  {
-    "description": "Multiple citation styles to generate. Each entry: apa, mla, bibtex, or ris.",
-    "items": {
-      "enum": [
-        "apa",
-        "mla",
-        "bibtex",
-        "ris"
-      ],
-      "type": "string"
-    },
-    "minItems": 1,
-    "type": "array"
-  }
-]New value: +[
+  {
+    "description": "Single citation style. One of: apa, mla, bibtex, ris, vancouver.",
+    "enum": [
+      "apa",
+      "mla",
+      "bibtex",
+      "ris",
+      "vancouver"
+    ],
+    "type": "string"
+  },
+  {
+    "description": "Multiple citation styles to generate. Each entry: apa, mla, bibtex, ris, or vancouver.",
+    "items": {
+      "enum": [
+        "apa",
+        "mla",
+        "bibtex",
+        "ris",
+        "vancouver"
+      ],
+      "type": "string"
+    },
+    "minItems": 1,
+    "type": "array"
+  }
+]

Previous value: -"Citation format(s) to generate — single style as a string or multiple as an array. Allowed values: apa, mla, bibtex, ris."New value: +"Citation format(s) to generate — single style as a string or multiple as an array. Allowed values: apa, mla, bibtex, ris, vancouver."

Added value: +{
+  "description": "Optional guidance when no citations were produced — points to discovery tools. Absent when at least one citation was produced.",
+  "type": "string"
+}

Previous value: -"Citation to match against PubMed. Must include at least one bibliographic field (journal, year, volume, firstPage, or authorName)."New value: +"Citation to match against PubMed. Must include at least journal or year — ECitMatch primary-keys on journal+volume+page, so author-only or volume-only inputs guarantee no match."

Previous value: -[
-  "query",
-  "hits",
-  "hitCount",
-  "cursorMark",
-  "appliedSources",
-  "searchUrl"
-]New value: +[
+  "hits",
+  "cursorMark",
+  "searchUrl",
+  "query",
+  "hitCount",
+  "appliedSources"
+]

Previous value: -[
-  "query",
-  "effectiveQuery",
-  "appliedFilters",
-  "totalFound",
-  "offset",
-  "pmids",
-  "summaries",
-  "searchUrl"
-]New value: +[
+  "query",
+  "offset",
+  "pmids",
+  "summaries",
+  "searchUrl",
+  "effectiveQuery",
+  "totalFound",
+  "appliedFilters"
+]

Removed value: -false

Added value: +{
+  "description": "Filter by author name (e.g. \"Smith J\")",
+  "type": "string"
+}

Removed value: -false

Previous value: -"Defines an optional date range for the search."New value: +"Filter by date range"

Previous value: -"The type of date to filter by: 'pdat' (Publication Date), 'mdat' (Modification Date), 'edat' (Entrez Date). Default is 'pdat'."New value: +"Date type: pdat (publication), mdat (modification), edat (entrez)"

Previous value: -"The end date for the search range (YYYY, YYYY/MM, or YYYY/MM/DD)."New value: +"End date (YYYY/MM/DD, YYYY/MM, or YYYY)"

Removed value: -"^\\d{4}(\\/\\d{2}(\\/\\d{2})?)?$"

Previous value: -"The start date for the search range (YYYY, YYYY/MM, or YYYY/MM/DD)."New value: +"Start date (YYYY/MM/DD, YYYY/MM, or YYYY)"

Removed value: -"^\\d{4}(\\/\\d{2}(\\/\\d{2})?)?$"

Added value: +[
+  "minDate",
+  "maxDate"
+]

Removed value: -{
-  "default": 0,
-  "description": "Number of top PMIDs for which to fetch brief summaries using ESummary. Set to 0 to disable. Max 50. Default 0.",
-  "maximum": 50,
-  "minimum": 0,
-  "type": "integer"
-}

Removed value: -{
-  "description": "An array of publication types to filter by (e.g., [\"Review\", \"Clinical Trial\"]).",
-  "items": {
-    "type": "string"
-  },
-  "type": "array"
-}

Added value: +{
+  "description": "Only include free full text articles",
+  "type": "boolean"
+}

Added value: +{
+  "description": "Only include articles with abstracts",
+  "type": "boolean"
+}

Added value: +{
+  "description": "Filter by journal name",
+  "type": "string"
+}

Added value: +{
+  "description": "Filter by language (e.g. \"english\")",
+  "type": "string"
+}

Previous value: -"Maximum number of articles to retrieve. Corresponds to ESearch's 'retmax' parameter. Default is 20, max is 1000."New value: +"Maximum results to return"

Removed value: -0

Added value: +1

Added value: +{
+  "description": "Filter by MeSH terms",
+  "items": {
+    "type": "string"
+  },
+  "type": "array"
+}

Added value: +{
+  "default": 0,
+  "description": "Result offset for pagination (0-based)",
+  "maximum": 9007199254740991,
+  "minimum": 0,
+  "type": "integer"
+}

Added value: +{
+  "description": "Filter by publication type (e.g. \"Review\", \"Clinical Trial\", \"Meta-Analysis\")",
+  "items": {
+    "type": "string"
+  },
+  "type": "array"
+}

Added value: +{
+  "description": "PubMed search query (supports full NCBI syntax)",
+  "minLength": 1,
+  "type": "string"
+}

Removed value: -{
-  "description": "The primary keyword or phrase to search for in PubMed. Must be at least 3 characters long.",
-  "minLength": 3,
-  "type": "string"
-}

Added value: +{
+  "default": "relevance",
+  "description": "Sort order: relevance (default), pub_date (newest first), author, or journal",
+  "enum": [
+    "relevance",
+    "pub_date",
+    "author",
+    "journal"
+  ],
+  "type": "string"
+}

Removed value: -{
-  "default": "relevance",
-  "description": "Sorting criteria for results. Options: 'relevance' (default), 'pub_date', 'author', 'journal_name'.",
-  "enum": [
-    "relevance",
-    "pub_date",
-    "author",
-    "journal_name"
-  ],
-  "type": "string"
-}

Added value: +{
+  "description": "Filter by species",
+  "enum": [
+    "humans",
+    "animals"
+  ],
+  "type": "string"
+}

Added value: +{
+  "default": 0,
+  "description": "Fetch brief summaries for top N results (0 = PMIDs only)",
+  "maximum": 50,
+  "minimum": 0,
+  "type": "integer"
+}

Previous value: -[
-  "queryTerm"
-]New value: +[
+  "query"
+]

Previous value: -nullNew value: +{
+  "$schema": "http://json-schema.org/draft-07/schema#",
+  "additionalProperties": false,
+  "properties": {
+    "offset": {
+      "description": "Result offset used",
+      "type": "number"
+    },
+    "pmids": {
+      "description": "PubMed IDs",
+      "items": {
+        "type": "string"
+      },
+      "type": "array"
+    },
+    "query": {
+      "description": "Original query",
+      "type": "string"
+    },
+    "searchUrl": {
+      "description": "PubMed search URL",
+      "type": "string"
+    },
+    "summaries": {
+      "description": "Brief summaries (empty array when summaryCount is 0)",
+      "items": {
+        "additionalProperties": false,
+        "properties": {
+          "authors": {
+            "description": "Formatted author string",
+            "type": "string"
+          },
+          "doi": {
+            "description": "DOI",
+            "type": "string"
+          },
+          "pmcId": {
+            "description": "PMC ID",
+            "type": "string"
+          },
+          "pmcUrl": {
+            "description": "PMC URL",
+            "type": "string"
+          },
+          "pmid": {
+            "description": "PubMed ID",
+            "type": "string"
+          },
+          "pubDate": {
+            "description": "Publication date",
+            "type": "string"
+          },
+          "pubmedUrl": {
+            "description": "PubMed URL",
+            "type": "string"
+          },
+          "source": {
+            "description": "Journal source",
+            "type": "string"
+          },
+          "title": {
+            "description": "Article title",
+            "type": "string"
+          }
+        },
+        "required": [
+          "pmid"
+        ],
+        "type": "object"
+      },
+      "type": "array"
+    },
+    "totalFound": {
+      "description": "Total matching articles",
+      "type": "number"
+    }
+  },
+  "required": [
+    "query",
+    "totalFound",
+    "offset",
+    "pmids",
+    "summaries",
+    "searchUrl"
+  ],
+  "type": "object"
+}