Medical Terminologies MCP

ICD-11 Postcoordination Options

icd11_postcoordination

Read-onlyIdempotent

Lists allowed postcoordination axes for an ICD-11 stem code so you can see required and optional dimensions before building a composite code.

Instructions

List the postcoordination axes WHO allows for one ICD-11 stem code (MMS linearization, pinned release).

Postcoordination means attaching extra detail to a stem code — severity, laterality, anatomy, causing agent, etc. — to build a composite (cluster) code.

Use this tool to:

See which axes a stem code accepts before building a composite code
Check which axes are REQUIRED vs optional
See whether an axis takes one or several values, and how many values it offers

Provide an ICD-11 code (e.g., "BA00"). Returns one entry per axis with axis_name, required, allow_multiple and value_count — the count of allowed values, not the values themselves. A code with no postcoordination, or one WHO does not know, returns an empty axes list (not an error), so check the code with icd11_lookup if the list is unexpectedly empty.

When NOT to use: this does not build or validate a composite code, and it does not list the allowed values; to get a code from a disease name, use icd11_search.

Input Schema

Name	Required	Description	Default
`code`	Yes	ICD-11 code to get postcoordination info for

Output Schema

Name	Required	Description
`axes`	Yes	Postcoordination axes the WHO allows for this code; empty when it has none or the WHO has no postcoordination info for it.
`code`	Yes	The ICD-11 code as submitted.
`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.

Changed2 schema fields changedv2.4.0Oct 29, 2026

addedOutput schema / properties / axes / description

Added value: +"Postcoordination axes the WHO allows for this code; empty when it has none or the WHO has no postcoordination info for it."

addedOutput schema / properties / code / description
```
Added value: +"The ICD-11 code as submitted."
```

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"
+}

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
```
Changed4 schema fields changedv1.9.1Sep 1, 2026
- 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"
+]
```

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: -[
-  "code",
-  "axes"
-]New value: +[
+  "code",
+  "axes",
+  "provenance",
+  "attribution"
+]

Changed2 schema fields changedv1.5.7Jun 21, 2026

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

changedOutput schema / properties / axes / items / properties / value_count / anyOf

Previous value: -[
-  {
-    "type": "integer"
-  },
-  {
-    "type": "null"
-  }
-]New value: +[
+  {
+    "maximum": 9007199254740991,
+    "minimum": -9007199254740991,
+    "type": "integer"
+  },
+  {
+    "type": "null"
+  }
+]

First observedv1.2.1May 11, 2026

TDQS

A4.9/5.0

Behavior5/5

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

Beyond the readOnly/idempotent/openWorld annotations, the description discloses non-obvious behavior: it covers only MMS linearization at the pinned release, unknown or non-postcoordinated codes return an empty axes list rather than an error, and value_count is a count rather than the values. These are exactly the surprises that would otherwise cause an agent to mis-handle a response.

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 definition, then usage bullets, then return behavior, then exclusions. The middle paragraph explaining postcoordination is functional domain context rather than padding, and each subsequent sentence introduces a distinct fact.

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?

An output schema exists, yet the description still summarizes the returned fields and their meaning, plus the empty-list edge case. For a single-parameter read tool with full annotations, there is no gap an agent would need to guess at before calling.

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% and the single parameter is documented there, so the baseline is 3. The description adds a concrete code format example ('BA00') and ties the parameter to a validation path (check the code with icd11_lookup if the result is unexpectedly empty), which is modest but real added meaning.

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?

The opening sentence names a specific verb+resource ('List the postcoordination axes') scoped to one ICD-11 stem code, and the following paragraph defines what postcoordination actually is. An agent can distinguish this from icd11_lookup, icd11_hierarchy and icd11_search 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?

Three explicit 'Use this tool to' bullets give positive triggers (check axes before building a composite, check required vs optional, check cardinality). The 'When NOT to use' block names concrete alternatives — icd11_lookup for code verification, icd11_search for name-to-code — leaving nothing to inference.

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