Medical Terminologies MCP

List ICD-11 Chapters

icd11_chapters

Read-onlyIdempotent

List all ICD-11 top-level chapters to get an overview of the classification, find the chapter for a body system or condition, and get URIs for deeper hierarchy lookups.

Instructions

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.

Input Schema

TableJSON 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

TableJSON Schema

Name	Required	Description
`chapters`	Yes
`provenance`	Yes	Provenance block (contract v1.1): 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.

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
```
Changed12 schema fields changedv1.9.1Sep 1, 2026
- removedOutput schema / properties / chapters / items / properties / code / anyOf
```
Removed value: -[
-  {
-    "type": "string"
-  },
-  {
-    "type": "null"
-  }
-]
```
- addedOutput schema / properties / chapters / items / properties / code / type
```
Added value: +[
+  "string",
+  "null"
+]
```
- removedOutput schema / properties / chapters / items / properties / code_range / anyOf
```
Removed value: -[
-  {
-    "type": "string"
-  },
-  {
-    "type": "null"
-  }
-]
```
- addedOutput schema / properties / chapters / items / properties / code_range / type
```
Added value: +[
+  "string",
+  "null"
+]
```
- removedOutput schema / properties / chapters / items / properties / error / anyOf
```
Removed value: -[
-  {
-    "type": "string"
-  },
-  {
-    "type": "null"
-  }
-]
```
- addedOutput schema / properties / chapters / items / properties / error / type
```
Added value: +[
+  "string",
+  "null"
+]
```
- removedOutput schema / properties / chapters / items / properties / title / anyOf
```
Removed value: -[
-  {
-    "type": "string"
-  },
-  {
-    "type": "null"
-  }
-]
```
- addedOutput schema / properties / chapters / items / properties / title / 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"
+]
```

Changed4 schema fields changedv1.8.0Aug 10, 2026

changedInput schema / properties / language / description

Previous value: -"Language code (default: en)"New value: +"Language code (default: en). Returns the source's OFFICIAL translation when it exists (e.g. 'pt' for official Portuguese); content is never machine-translated."

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: -[
-  "chapters"
-]New value: +[
+  "chapters",
+  "provenance",
+  "attribution"
+]

Changed11 schema fields changedv1.5.7Jun 21, 2026
- removedInput schema / additionalProperties
```
Removed value: -false
```
- addedOutput schema / properties / chapters / items / properties / code / anyOf
```
Added value: +[
+  {
+    "type": "string"
+  },
+  {
+    "type": "null"
+  }
+]
```
- removedOutput schema / properties / chapters / items / properties / code / type
```
Removed value: -[
-  "string",
-  "null"
-]
```
- addedOutput schema / properties / chapters / items / properties / code_range / anyOf
```
Added value: +[
+  {
+    "type": "string"
+  },
+  {
+    "type": "null"
+  }
+]
```
- removedOutput schema / properties / chapters / items / properties / code_range / type
```
Removed value: -[
-  "string",
-  "null"
-]
```
- addedOutput schema / properties / chapters / items / properties / error / anyOf
```
Added value: +[
+  {
+    "type": "string"
+  },
+  {
+    "type": "null"
+  }
+]
```
- removedOutput schema / properties / chapters / items / properties / error / type
```
Removed value: -[
-  "string",
-  "null"
-]
```
- addedOutput schema / properties / chapters / items / properties / number / maximum
```
Added value: +9007199254740991
```
- addedOutput schema / properties / chapters / items / properties / number / minimum
```
Added value: +-9007199254740991
```
- addedOutput schema / properties / chapters / items / properties / title / anyOf
```
Added value: +[
+  {
+    "type": "string"
+  },
+  {
+    "type": "null"
+  }
+]
```
- removedOutput schema / properties / chapters / items / properties / title / type
```
Removed value: -[
-  "string",
-  "null"
-]
```
First observedv1.2.1May 11, 2026

TDQS

A4.7/5.0

Behavior5/5

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

Goes well beyond annotations: exact result size (28 entries, no pagination), composition (01-26 plus V and X), per-chapter fetch semantics with partial-failure behavior (entry keeps URI and carries an `error`), caching behavior, and official-translation-only guarantee. These are non-obvious operational traits an agent needs.

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

Conciseness5/5

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

Front-loaded with the core action, then bulleted use cases, return shape, and exclusions. Every sentence carries distinct information; nothing is padding.

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?

With an output schema present, return values need not be re-explained, yet the description still covers count, failure modes, and caching. Nothing an agent needs to call this correctly is missing.

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

Parameters3/5

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

Schema coverage is 100% and the schema already documents the language enum, default, and the no-machine-translation rule. The description's `language: "pt"` example and caching note add only marginal value over the schema, so baseline 3 applies.

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?

States a specific verb+resource ('List all ICD-11 chapters (top-level categories) of the pinned WHO release') and immediately scopes it against siblings. An agent can distinguish it from icd11_search, icd11_hierarchy, and cid10_chapters without opening any schema.

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?

Explicitly enumerates three use cases (overview, chapter discovery, URI retrieval for drill-down) and a 'When NOT to use' block naming the correct alternatives (icd11_search for diseases, cid10_chapters for CID-10). Routing is fully specified.

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