Medical Terminologies MCP

List ICD-11 Chapters

icd11_chapters

Read-onlyIdempotent

List all ICD-11 chapters (top-level categories) of the pinned WHO release.

Use this tool to:

Get an overview of ICD-11 structure
Find which chapter covers a body system or condition type
Get chapter URIs to drill down with icd11_hierarchy (direction 'children')

Returns 28 entries in one response, no pagination — chapters 01-26 plus the supplementary sections V (functioning) and X (extension codes) — each with number, code, title and URI. Each chapter is fetched separately from WHO; if one fetch fails, that entry keeps its URI and carries an error instead of a title, and the rest still come back. Set language for WHO's official translations (e.g. language: "pt"); the result is cached, so repeated calls are cheap.

When NOT to use: to find a specific disease, use icd11_search; for the Brazilian CID-10 (ICD-10) chapters, use cid10_chapters.

Tool call template

This tool declares no required parameters. Add optional parameters from the input schema as needed.

{
  "id": 1,
  "jsonrpc": "2.0",
  "method": "tools/call",
  "params": {
    "arguments": {},
    "name": "icd11_chapters"
  }
}

Input Schema

Name	Required	Description	Default
`language`	No	Language code (default: en). Returns the source's OFFICIAL translation when it exists (e.g. 'pt' for official Portuguese); content is never machine-translated.	en

Output Schema

Name	Required	Description
`chapters`	Yes	Top-level ICD-11 MMS chapters in WHO order; a chapter the WHO failed to return keeps its number and URI, with error set and the other fields null.
`provenance`	Yes	Provenance block: source, URL, data vintage, extraction instant, origin diagnostics, citation, license
`attribution`	Yes	Canonical source URLs of this response (attribution list)

Schema Changelog

Changes observed during successful MCP inspections.

Changed1 schema field changedOct 28, 2026

addedOutput schema / properties / chapters / description

Added value: +"Top-level ICD-11 MMS chapters in WHO order; a chapter the WHO failed to return keeps its number and URI, with error set and the other fields null."

Changed1 schema field changedOct 16, 2026

changedOutput schema / properties / provenance / properties / notices / description

Previous value: -"Notices the source publishes alongside the data (license statements, caveats), verbatim. Absent when there is none"New value: +"Caveats the source publishes about the data, verbatim (license statements are not repeated here; see the info://licenses resource). Absent when there is none"

Changed7 schema fields changedOct 8, 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": "Notices the source publishes alongside the data (license statements, caveats), verbatim. 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 changedOct 6, 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"
+}

Changed3 schema fields changedSep 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 changedSep 11, 2026
- addedInput schema / additionalProperties
```
Added value: +false
```
First observedSep 6, 2026

TDQS

A4.8/5.0

Behavior5/5

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

Goes well beyond the readOnly/idempotent annotations: it discloses the exact result size (28 entries, no pagination), the composition of the list (01-26 plus V and X), and the partial-failure contract where an individual chapter keeps its URI and carries an `error` instead of a title. It also notes WHO-side per-chapter fetching and result caching, which materially affects retry and cost decisions.

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 purpose, then scenarios, then return/failure behavior, then exclusions — a logical order. The field enumeration ('number, code, title and URI') is redundant given the output schema, but the rest of the prose earns its place.

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 single-parameter, read-only listing tool with an output schema and full annotations, everything an agent needs is present: scope, result size, failure semantics, caching, language behavior, and sibling routing. No gap remains that would cause a misinvocation.

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% with an enum, so the baseline is 3; the description still adds practical value by showing a concrete invocation (`language: "pt"`) and tying the parameter to a caching consequence. It slightly repeats the schema's 'official translation' wording rather than extending it, keeping it out of 5 territory.

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

Purpose5/5

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

Opens with a specific verb and resource ('List all ICD-11 chapters (top-level categories) of the pinned WHO release'), plus a parenthetical that defines what a chapter is. It is unambiguous against icd11_search and cid10_chapters, which are named explicitly later.

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?

Provides three explicit 'use this tool to' scenarios (structure overview, body-system routing, obtaining URIs to drill down) and a 'When NOT to use' block that names the correct alternatives (icd11_search for diseases, cid10_chapters for CID-10). Nothing is left to inference.

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

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