Previous value: -"Filter by domain category (e.g., \"NNDSS\", \"Vaccinations\", \"Behavioral Risk Factors\")."New value: +"Filter by domain category (e.g., \"NNDSS\", \"Vaccinations\", \"Behavioral Risk Factors\"). Values come from the catalog's own vocabulary and are matched exactly, including case — \"Vaccinations\" matches 89 entries while \"Vaccination\" matches none. Call cdc_list_catalog_vocabulary for every value with its entry count rather than guessing at one."

Previous value: -"Filter by domain tags (e.g., [\"covid19\", \"surveillance\"]). Tags widen the search instead of narrowing it — a dataset matches when it carries any one of them, so every tag added returns more results, and an unrecognized tag matches nothing and leaves the result set unchanged. Values match the catalog's own tag vocabulary, case-insensitively; the tags field on each result shows which values are in use. To narrow, combine tags with query or category, which intersect with the tag set."New value: +"Filter by domain tags (e.g., [\"covid19\", \"surveillance\"]). Tags widen the search instead of narrowing it — a dataset matches when it carries any one of them, so every tag added returns more results, and an unrecognized tag matches nothing and leaves the result set unchanged. Values match the catalog's own tag vocabulary, case-insensitively; call cdc_list_catalog_vocabulary for the values in use with their entry counts, or read the tags field on any result. To narrow, combine tags with query or category, which intersect with the tag set."

Previous value: -"Dataset description when provided by the catalog, truncated to 300 characters. Fetch the full text via cdc_get_dataset_schema."New value: +"Dataset description when provided by the catalog, as plain text — markup stripped and entity references decoded — then truncated to 300 characters, so the limit bounds visible text. Fetch the full text via cdc_get_dataset_schema."

Previous value: -"Guidance when the page came back empty — how to broaden a search that matched nothing, where to check tag values when a tag filter was applied, or the size of the result set when the offset ran past its end."New value: +"Guidance when the page came back empty — the catalog values closest to a category or tag filter that matched nothing, each with its entry count; how to broaden a search when no value is close; or the size of the result set when the offset ran past its end."

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": [
+      "datasets",
+      "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: `rate_limited`: Socrata API returns 429 Too Many Requests. `dataset_not_found`: Socrata returned 404 for the catalog endpoint itself — the Discovery API address is wrong or the service moved. `access_denied`: Socrata returned 403 — the catalog refused this request rather than failing to serve it. `upstream_error`: Socrata catalog API returned a 5xx server error. `page_out_of_range`: offset plus limit exceeds 10000, which Socrata's catalog rejects outright. `invalid_query`: Catalog API returned 400 — typically a malformed query or invalid filter value. Other values are possible when a failure originates below the handler.",
+          "examples": [
+            "rate_limited",
+            "dataset_not_found",
+            "access_denied",
+            "upstream_error",
+            "page_out_of_range",
+            "invalid_query"
+          ],
+          "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: -[
-  "datasets",
-  "totalCount",
-  "appliedFilters"
-]

Previous value: -"CDC Socrata portal to search. \"data.cdc.gov\" (default) is the main CDC catalog; \"chronicdata.cdc.gov\" hosts chronic-disease and small-area datasets (PLACES, the Heart Disease & Stroke Atlas, Environmental Public Health Tracking)."New value: +"CDC Socrata host to search. \"data.cdc.gov\" (default) and \"chronicdata.cdc.gov\" front the same catalog and return the same entries, so switching hosts neither widens nor narrows a search — chronic-disease and small-area collections such as PLACES, the Heart Disease & Stroke Atlas, and Environmental Public Health Tracking are found from either."

Previous value: -"Results to return (default 10, max 100)."New value: +"Results to return (default 10, max 100). offset plus limit must not exceed 10000."

Previous value: -"Pagination offset for browsing beyond first page (max 9999)."New value: +"Pagination offset for browsing beyond first page (max 9999). offset plus limit must not exceed 10000; both CDC portals hold well under two thousand entries, so offsets near that ceiling page past the end of the catalog."

Previous value: -"Filter by domain tags (e.g., [\"covid19\", \"surveillance\"])."New value: +"Filter by domain tags (e.g., [\"covid19\", \"surveillance\"]). Tags widen the search instead of narrowing it — a dataset matches when it carries any one of them, so every tag added returns more results, and an unrecognized tag matches nothing and leaves the result set unchanged. Values match the catalog's own tag vocabulary, case-insensitively; the tags field on each result shows which values are in use. To narrow, combine tags with query or category, which intersect with the tag set."

Previous value: -"Filters applied to this query; absent fields indicate no filter on that dimension."New value: +"Filters applied to this query; absent fields indicate no filter on that dimension. Query, category, and tags intersect with each other, but multiple tags union."

Previous value: -"Tag filters used."New value: +"Tag filters used — a dataset matched when it carried any one of them."

Added value: +{
+  "description": "Catalog asset type as Socrata reports it — \"dataset\", \"filter\", \"chart\", \"map\", \"story\", \"file\", or \"href\". Descriptive only: \"filter\" entries carry real columns and query normally, while \"chart\" and \"map\" entries do not. Read columnCount, not this field, to decide whether an entry is queryable.",
+  "type": "string"
+}

Previous value: -"Number of columns in the dataset when reported by the catalog."New value: +"Number of columns in the dataset when reported by the catalog. A count of 0 means the entry is not tabular — cdc_get_dataset_schema and cdc_query_dataset return no usable data for it."

Previous value: -"Guidance when no datasets matched — echoes the applied filters and suggests how to broaden the search."New value: +"Guidance when the page came back empty — how to broaden a search that matched nothing, where to check tag values when a tag filter was applied, or the size of the result set when the offset ran past its end."

Added value: +{
+  "default": "dataset_id",
+  "description": "Result ordering. \"dataset_id\" (default) sorts deterministically by each dataset's unique catalog ID — required for stable offset pagination, since consecutive pages form a gap-free, duplicate-free traversal. \"relevance\" returns best-match ranking for keyword search but is not stably paginable across pages, so walking offsets can skip or repeat datasets.",
+  "enum": [
+    "dataset_id",
+    "relevance"
+  ],
+  "type": "string"
+}

Added value: +{
+  "default": "data.cdc.gov",
+  "description": "CDC Socrata portal to search. \"data.cdc.gov\" (default) is the main CDC catalog; \"chronicdata.cdc.gov\" hosts chronic-disease and small-area datasets (PLACES, the Heart Disease & Stroke Atlas, Environmental Public Health Tracking).",
+  "enum": [
+    "data.cdc.gov",
+    "chronicdata.cdc.gov"
+  ],
+  "type": "string"
+}

Added value: +{
+  "description": "Number of columns in the dataset when reported by the catalog.",
+  "type": "number"
+}

Removed value: -{
-  "description": "Available column field names when provided.",
-  "items": {
-    "type": "string"
-  },
-  "type": "array"
-}

Added value: +{
+  "description": "First 8 column field names as a preview. Call cdc_get_dataset_schema for the full column list with data types.",
+  "items": {
+    "type": "string"
+  },
+  "type": "array"
+}

Removed value: -{
-  "description": "Column data types (parallel to columnNames) when provided.",
-  "items": {
-    "type": "string"
-  },
-  "type": "array"
-}

Previous value: -"Dataset description when provided by the catalog."New value: +"Dataset description when provided by the catalog, truncated to 300 characters. Fetch the full text via cdc_get_dataset_schema."

Previous value: -"Filters that were applied to this query; absent fields indicate no filter on that dimension."New value: +"Filters applied to this query; absent fields indicate no filter on that dimension."

Added value: +{
+  "description": "Guidance when no datasets matched — echoes the applied filters and suggests how to broaden the search.",
+  "type": "string"
+}

Previous value: -"Total matching datasets (for pagination)."New value: +"Total matching datasets in the catalog (for pagination)."

Previous value: -"Filters applied to this search (echoed for diagnostics)."New value: +"Filters that were applied to this query; absent fields indicate no filter on that dimension."

Previous value: -"Dataset name."New value: +"Dataset display name from the catalog (e.g., \"Provisional COVID-19 Deaths by Sex and Age\")."

Added value: +"A single dataset catalog entry."

Previous value: -"Domain category."New value: +"Domain category when provided."

Previous value: -"Available column field names."New value: +"Available column field names when provided."

Removed value: -"Column name"

Previous value: -"Column data types (parallel to columnNames)."New value: +"Column data types (parallel to columnNames) when provided."

Removed value: -"Column type"

Previous value: -"Dataset description."New value: +"Dataset description when provided by the catalog."

Previous value: -"Total page views."New value: +"Total page views when provided."

Previous value: -"Domain tags."New value: +"Domain tags when provided."

Removed value: -"Tag"

Previous value: -"Last data update timestamp."New value: +"Last data update timestamp when provided."

Previous value: -[
-  "id",
-  "name",
-  "description",
-  "category",
-  "tags",
-  "columnNames",
-  "columnTypes",
-  "updatedAt",
-  "pageViews"
-]New value: +[
+  "id",
+  "name"
+]