Medical Terminologies MCP

Terminology Version Diff

terminology_diff

Read-onlyIdempotent

Reports available version-diff data between two terminology releases and points to official changelogs; for ICD-10 vs ICD-11, summarizes mapped categories, 1:1 vs split matches, and alternatives.

Instructions

Report what diff data is available between two versions of a terminology.

For most terminologies this is guidance only — the server doesn't ship historical snapshots, so the tool points at the publisher's official changelog and explains the cadence. bundled_versions lists the version(s) this server actually has on hand.

For ICD-10 vs ICD-11 specifically, the tool surfaces a real cross-revision summary from the bundled WHO transition tables (the ICD-10 → ICD-11 case is a structural diff between two WHO revisions). Use terminology: "icd10" with no to_version to get the cross-revision summary: total mapped ICD-10 categories, how many are 1:1 vs split into multiple ICD-11 codes, and the average number of alternatives when split.

Inputs:

terminology (required): which terminology to report on.
from_version (optional): the version you have data from. If omitted, the tool reports against the currently-bundled version.
to_version (optional): the version you want to compare to. If omitted, the tool reports against the publisher's latest known release.

This tool is intentionally a metadata + guidance layer, not a diff engine — for terminologies that change frequently (LOINC, RxNorm, MeSH), the publisher's official changelog is the authoritative source.

Input Schema

Name	Required	Description
`to_version`	No	Version you want to compare to. Optional.
`terminology`	Yes	Which terminology to report on.
`from_version`	No	Version you have data from. Optional; behavior depends on terminology.

Output Schema

Name	Required	Description
`message`	Yes	Explanation of the answer: what was computed, or why no diff is available and where to look instead.
`provenance`	Yes	Provenance block: source, URL, data vintage, extraction instant, origin diagnostics, citation, license
`to_version`	Yes	The to_version requested; null when not given.
`attribution`	Yes	Canonical source URLs of this response (attribution list)
`terminology`	Yes	The terminology reported on, as submitted.
`from_version`	Yes	The from_version requested (for icd10, the bundled ICD-10 release when not given); null when not given.
`changelog_url`	Yes	Publisher's official changelog for the terminology; null when none is known.
`diff_available`	Yes	True when this server has the data to compute a real diff for the requested terminology. False = guidance-only response.
`bundled_versions`	Yes	Versions of this terminology bundled in the server; empty when the server queries the live upstream.
`cross_revision_summary`	Yes	Populated only for terminology="icd10" today — the bundled WHO ICD-10 → ICD-11 transition tables let us surface a real structural diff between the two WHO revisions.

Schema Changelog

Changes observed during successful MCP inspections.

Changed6 schema fields changedv2.4.0Oct 29, 2026

addedOutput schema / properties / bundled_versions / description

Added value: +"Versions of this terminology bundled in the server; empty when the server queries the live upstream."

addedOutput schema / properties / changelog_url / description

Added value: +"Publisher's official changelog for the terminology; null when none is known."

addedOutput schema / properties / from_version / description

Added value: +"The from_version requested (for icd10, the bundled ICD-10 release when not given); null when not given."

addedOutput schema / properties / message / description

Added value: +"Explanation of the answer: what was computed, or why no diff is available and where to look instead."

addedOutput schema / properties / terminology / description

Added value: +"The terminology reported on, as submitted."

addedOutput schema / properties / to_version / description

Added value: +"The to_version requested; null when not given."

Changed7 schema fields changedv2.3.0Oct 16, 2026

changedOutput schema / properties / provenance / description

Previous value: -"Provenance block (contract v1.1): source, URL, data vintage, extraction instant, origin diagnostics, citation, license"New value: +"Provenance block: source, URL, data vintage, extraction instant, origin diagnostics, citation, license"

addedOutput schema / properties / provenance / properties / derivation_note

Added value: +{
+  "description": "What this server computed; present together with derived",
+  "type": "string"
+}

addedOutput schema / properties / provenance / properties / derived

Added value: +{
+  "description": "Present (true) only when this server computed the value (e.g. a ranking or summary statistics) instead of passing on what the source returned",
+  "type": "boolean"
+}

changedOutput schema / properties / provenance / properties / field_sources / description

Previous value: -"Present only when the response joins parts from different origins or extraction instants (contract v1.2): for each group of fields, its URL, extraction instant and whether it came from cache. Absent in single-origin responses"New value: +"Present only when the response joins parts from different origins or extraction instants: for each group of fields, its URL, extraction instant and whether it came from cache. Absent in single-origin responses"

addedOutput schema / properties / provenance / properties / notices

Added value: +{
+  "description": "Caveats the source publishes about the data, verbatim (license statements are not repeated here; see the info://licenses resource). Absent when there is none",
+  "items": {
+    "type": "string"
+  },
+  "minItems": 1,
+  "type": "array"
+}

changedOutput schema / properties / provenance / properties / retrieval / description

Previous value: -"Origin diagnostics of THIS source in this call (contract v1.1): requests made to the upstream, attempts summed across retries, anomalies worked around (kind + count); unstable=true when any anomaly happened. null when nothing was measured (bundled dataset, or response served entirely from cache)"New value: +"Origin diagnostics of THIS source in this call: requests made to the upstream, attempts summed across retries, anomalies worked around (kind + count); unstable=true when any anomaly happened. null when nothing was measured (bundled dataset, or response served entirely from cache)"

addedOutput schema / properties / provenance / properties / revision

Added value: +{
+  "additionalProperties": false,
+  "description": "Whether the data can still change at the source: current = the version in force, the source may revise it; provisional = preliminary; final = will not change. Absent when unknown",
+  "properties": {
+    "note": {
+      "description": "O específico da fonte: o que revisa, quando, por quê",
+      "type": [
+        "string",
+        "null"
+      ]
+    },
+    "status": {
+      "description": "current = versão vigente, a fonte pode revisá-la; provisional = preliminar, incompleta ou sujeita a mudança (não compare como se fosse fechada); final = não muda mais, declarado pela fonte",
+      "enum": [
+        "current",
+        "provisional",
+        "final"
+      ],
+      "type": "string"
+    }
+  },
+  "required": [
+    "status",
+    "note"
+  ],
+  "type": "object"
+}

Changed1 schema field changedv2.1.1Oct 7, 2026

addedOutput schema / properties / provenance / properties / field_sources

Added value: +{
+  "description": "Present only when the response joins parts from different origins or extraction instants (contract v1.2): for each group of fields, its URL, extraction instant and whether it came from cache. Absent in single-origin responses",
+  "items": {
+    "additionalProperties": false,
+    "description": "Proveniência de um grupo de campos da resposta: de onde veio e quando foi extraído",
+    "properties": {
+      "data_vintage": {
+        "description": "Vintage/competência da sub-fonte",
+        "type": [
+          "string",
+          "null"
+        ]
+      },
+      "dataset_id": {
+        "description": "Identificador do conjunto da sub-fonte",
+        "type": [
+          "string",
+          "null"
+        ]
+      },
+      "fields": {
+        "description": "Campos do payload atribuídos a esta sub-fonte",
+        "items": {
+          "type": "string"
+        },
+        "minItems": 1,
+        "type": "array"
+      },
+      "retrieved_at": {
+        "description": "ISO-8601 da extração desta sub-fonte na origem",
+        "type": [
+          "string",
+          "null"
+        ]
+      },
+      "served_from_cache": {
+        "description": "true se esta sub-fonte veio do cache do servidor (retrieved_at é o da extração original); false se foi buscada nesta chamada; null se o servidor não distingue",
+        "type": [
+          "boolean",
+          "null"
+        ]
+      },
+      "source_url": {
+        "description": "URL canônica da sub-fonte que originou estes campos",
+        "type": "string"
+      }
+    },
+    "required": [
+      "fields",
+      "source_url",
+      "dataset_id",
+      "data_vintage",
+      "retrieved_at"
+    ],
+    "type": "object"
+  },
+  "minItems": 1,
+  "type": "array"
+}

Changed2 schema fields changedv2.0.0Oct 4, 2026

changedInput schema / properties / terminology / enum

Previous value: -[
-  "icd11",
-  "icd10",
-  "snomed",
-  "loinc",
-  "rxnorm",
-  "mesh",
-  "atc",
-  "cid10"
-]New value: +[
+  "icd11",
+  "icd10",
+  "loinc",
+  "rxnorm",
+  "mesh",
+  "atc",
+  "cid10"
+]

changedOutput schema / properties / terminology / enum

Previous value: -[
-  "icd11",
-  "icd10",
-  "snomed",
-  "loinc",
-  "rxnorm",
-  "mesh",
-  "atc",
-  "cid10"
-]New value: +[
+  "icd11",
+  "icd10",
+  "loinc",
+  "rxnorm",
+  "mesh",
+  "atc",
+  "cid10"
+]

Changed3 schema fields changedv1.15.0Sep 27, 2026

changedOutput schema / properties / provenance / description

Previous value: -"Provenance block (contract v1.0): source, URL, data vintage, extraction instant, citation, license"New value: +"Provenance block (contract v1.1): source, URL, data vintage, extraction instant, origin diagnostics, citation, license"

addedOutput schema / properties / provenance / properties / retrieval

Added value: +{
+  "anyOf": [
+    {
+      "additionalProperties": false,
+      "properties": {
+        "anomalies": {
+          "description": "Anomalias superadas até o sucesso, somadas por classe, em ordem fixa; [] se nenhuma",
+          "items": {
+            "additionalProperties": false,
+            "properties": {
+              "count": {
+                "description": "Ocorrências desta classe na chamada",
+                "maximum": 9007199254740991,
+                "minimum": 1,
+                "type": "integer"
+              },
+              "kind": {
+                "description": "Classe da anomalia (vocabulário fechado do contrato)",
+                "enum": [
+                  "timeout",
+                  "network",
+                  "http_4xx",
+                  "http_5xx",
+                  "rate_limited",
+                  "malformed_body"
+                ],
+                "type": "string"
+              }
+            },
+            "required": [
+              "kind",
+              "count"
+            ],
+            "type": "object"
+          },
+          "type": "array"
+        },
+        "attempts": {
+          "description": "Tentativas somadas, incluindo as repetidas (>= requests)",
+          "maximum": 9007199254740991,
+          "minimum": 1,
+          "type": "integer"
+        },
+        "requests": {
+          "description": "Idas distintas à origem que compõem esta resposta (fatias, páginas)",
+          "maximum": 9007199254740991,
+          "minimum": 1,
+          "type": "integer"
+        },
+        "unstable": {
+          "description": "true se houve repetição (attempts > requests) ou alguma anomalia",
+          "type": "boolean"
+        }
+      },
+      "required": [
+        "requests",
+        "attempts",
+        "anomalies",
+        "unstable"
+      ],
+      "type": "object"
+    },
+    {
+      "type": "null"
+    }
+  ],
+  "description": "Origin diagnostics of THIS source in this call (contract v1.1): requests made to the upstream, attempts summed across retries, anomalies worked around (kind + count); unstable=true when any anomaly happened. null when nothing was measured (bundled dataset, or response served entirely from cache)"
+}

changedOutput schema / properties / provenance / required

Previous value: -[
-  "source",
-  "source_url",
-  "data_vintage",
-  "retrieved_at",
-  "citation",
-  "license"
-]New value: +[
+  "source",
+  "source_url",
+  "data_vintage",
+  "retrieved_at",
+  "retrieval",
+  "citation",
+  "license"
+]

Changed1 schema field changedv1.11.0Sep 15, 2026
- addedInput schema / additionalProperties
```
Added value: +false
```
Changed10 schema fields changedv1.9.1Sep 1, 2026
- removedOutput schema / properties / changelog_url / anyOf
```
Removed value: -[
-  {
-    "type": "string"
-  },
-  {
-    "type": "null"
-  }
-]
```
- addedOutput schema / properties / changelog_url / type
```
Added value: +[
+  "string",
+  "null"
+]
```
- removedOutput schema / properties / from_version / anyOf
```
Removed value: -[
-  {
-    "type": "string"
-  },
-  {
-    "type": "null"
-  }
-]
```
- addedOutput schema / properties / from_version / type
```
Added value: +[
+  "string",
+  "null"
+]
```
- removedOutput schema / properties / provenance / properties / data_vintage / anyOf
```
Removed value: -[
-  {
-    "type": "string"
-  },
-  {
-    "type": "null"
-  }
-]
```
- addedOutput schema / properties / provenance / properties / data_vintage / type
```
Added value: +[
+  "string",
+  "null"
+]
```
- removedOutput schema / properties / provenance / properties / license / anyOf
```
Removed value: -[
-  {
-    "type": "string"
-  },
-  {
-    "type": "null"
-  }
-]
```
- addedOutput schema / properties / provenance / properties / license / type
```
Added value: +[
+  "string",
+  "null"
+]
```
- removedOutput schema / properties / to_version / anyOf
```
Removed value: -[
-  {
-    "type": "string"
-  },
-  {
-    "type": "null"
-  }
-]
```
- addedOutput schema / properties / to_version / type
```
Added value: +[
+  "string",
+  "null"
+]
```

Changed3 schema fields changedv1.8.0Aug 10, 2026

addedOutput schema / properties / attribution

Added value: +{
+  "description": "Canonical source URLs of this response (attribution list)",
+  "items": {
+    "type": "string"
+  },
+  "type": "array"
+}

addedOutput schema / properties / provenance

Added value: +{
+  "additionalProperties": false,
+  "description": "Provenance block (contract v1.0): source, URL, data vintage, extraction instant, citation, license",
+  "properties": {
+    "citation": {
+      "description": "Ready-to-use citation/attribution string",
+      "type": "string"
+    },
+    "data_vintage": {
+      "anyOf": [
+        {
+          "type": "string"
+        },
+        {
+          "type": "null"
+        }
+      ],
+      "description": "Version/release of the data as exposed by the source; null when not exposed"
+    },
+    "license": {
+      "anyOf": [
+        {
+          "type": "string"
+        },
+        {
+          "type": "null"
+        }
+      ],
+      "description": "License / legal regime of the data"
+    },
+    "retrieved_at": {
+      "description": "Real instant of the upstream extraction (ISO-8601, UTC). Responses served from cache keep the ORIGINAL fetch instant.",
+      "type": "string"
+    },
+    "source": {
+      "description": "Official upstream source of this data",
+      "type": "string"
+    },
+    "source_url": {
+      "description": "Canonical URL of the source (API base or dataset release)",
+      "type": "string"
+    }
+  },
+  "required": [
+    "source",
+    "source_url",
+    "data_vintage",
+    "retrieved_at",
+    "citation",
+    "license"
+  ],
+  "type": "object"
+}

changedOutput schema / required

Previous value: -[
-  "terminology",
-  "from_version",
-  "to_version",
-  "diff_available",
-  "message",
-  "changelog_url",
-  "bundled_versions",
-  "cross_revision_summary"
-]New value: +[
+  "terminology",
+  "from_version",
+  "to_version",
+  "diff_available",
+  "message",
+  "changelog_url",
+  "bundled_versions",
+  "cross_revision_summary",
+  "provenance",
+  "attribution"
+]

Changed8 schema fields changedv1.5.7Jun 21, 2026

removedInput schema / additionalProperties
```
Removed value: -false
```

addedOutput schema / properties / changelog_url / anyOf

Added value: +[
+  {
+    "type": "string"
+  },
+  {
+    "type": "null"
+  }
+]

removedOutput schema / properties / changelog_url / type
```
Removed value: -[
-  "string",
-  "null"
-]
```

changedOutput schema / properties / cross_revision_summary / anyOf

Previous value: -[
-  {
-    "additionalProperties": false,
-    "properties": {
-      "avg_alternatives_when_split": {
-        "type": "number"
-      },
-      "icd10_categories_total": {
-        "type": "integer"
-      },
-      "one_to_many_splits": {
-        "type": "integer"
-      },
-      "one_to_one_mappings": {
-        "type": "integer"
-      }
-    },
-    "required": [
-      "icd10_categories_total",
-      "one_to_one_mappings",
-      "one_to_many_splits",
-      "avg_alternatives_when_split"
-    ],
-    "type": "object"
-  },
-  {
-    "type": "null"
-  }
-]New value: +[
+  {
+    "additionalProperties": false,
+    "properties": {
+      "avg_alternatives_when_split": {
+        "type": "number"
+      },
+      "icd10_categories_total": {
+        "maximum": 9007199254740991,
+        "minimum": -9007199254740991,
+        "type": "integer"
+      },
+      "one_to_many_splits": {
+        "maximum": 9007199254740991,
+        "minimum": -9007199254740991,
+        "type": "integer"
+      },
+      "one_to_one_mappings": {
+        "maximum": 9007199254740991,
+        "minimum": -9007199254740991,
+        "type": "integer"
+      }
+    },
+    "required": [
+      "icd10_categories_total",
+      "one_to_one_mappings",
+      "one_to_many_splits",
+      "avg_alternatives_when_split"
+    ],
+    "type": "object"
+  },
+  {
+    "type": "null"
+  }
+]

addedOutput schema / properties / from_version / anyOf

Added value: +[
+  {
+    "type": "string"
+  },
+  {
+    "type": "null"
+  }
+]

removedOutput schema / properties / from_version / type
```
Removed value: -[
-  "string",
-  "null"
-]
```

addedOutput schema / properties / to_version / anyOf

Added value: +[
+  {
+    "type": "string"
+  },
+  {
+    "type": "null"
+  }
+]

removedOutput schema / properties / to_version / type
```
Removed value: -[
-  "string",
-  "null"
-]
```

Addedv1.4.0May 12, 2026

TDQS

A4.5/5.0

Behavior5/5

Does the description disclose side effects, auth requirements, rate limits, or destructive behavior?

Goes well beyond the readOnly/idempotent annotations by disclosing the crucial behavioral caveat that the server ships no historical snapshots, that bundled_versions reveals what is actually on hand, and what the ICD-10 path returns (total mapped categories, 1:1 vs split counts, average alternatives). This prevents an agent from expecting a real diff.

Agents need to know what a tool does to the world before calling it. Descriptions should go beyond structured annotations to explain consequences.

Conciseness4/5

Is the description appropriately sized, front-loaded, and free of redundancy?

Front-loaded with the key caveat and organized with an Inputs list plus a closing summary. Slightly verbose — the final paragraph largely restates the opening "guidance only" framing — but the redundancy is mild and each block carries useful routing information.

Shorter descriptions cost fewer tokens and are easier for agents to parse. Every sentence should earn its place.

Completeness5/5

Given the tool's complexity, does the description cover enough for an agent to succeed on first attempt?

For a 3-parameter, read-only metadata tool with annotations and an output schema, the description covers scope, defaults, expected return shape for the non-trivial case, and explicit fallback guidance. Nothing an agent needs to call it correctly is missing.

Complex tools with many parameters or behaviors need more documentation. Simple tools need less. This dimension scales expectations accordingly.

Parameters4/5

Does the description clarify parameter syntax, constraints, interactions, or defaults beyond what the schema provides?

Schema coverage is 100%, so baseline is 3, but the description adds default semantics the schema only hints at: omitting from_version reports against the bundled version, omitting to_version reports against the publisher's latest known release, and terminology: "icd10" with no to_version triggers the cross-revision path.

Input schemas describe structure but not intent. Descriptions should explain non-obvious parameter relationships and valid value ranges.

Purpose4/5

Does the description clearly state what the tool does and how it differs from similar tools?

Clear specific verb + resource: reports what diff data is available between two versions of a terminology. It explicitly disclaims being a diff engine and frames itself as a metadata/guidance layer, which separates it functionally from map_icd10_to_icd11 and terminology_versions, though it never names those siblings directly.

Agents choose between tools based on descriptions. A clear purpose with a specific verb and resource helps agents select the right tool.

Usage Guidelines5/5

Does the description explain when to use this tool, when not to, or what alternatives exist?

It states exactly when this tool is useful (ICD-10 vs ICD-11 cross-revision summary) and when it is not (LOINC, RxNorm, MeSH — go to the publisher's official changelog instead). It also gives the concrete invocation recipe: terminology "icd10" with no to_version.

Agents often have multiple tools that could apply. Explicit usage guidance like "use X instead of Y when Z" prevents misuse.