Medical Terminologies MCP

MeSH Descriptor Details

mesh_descriptor

Read-onlyIdempotent

Retrieves detailed MeSH descriptor information by ID, including scope notes, tree hierarchy, related concepts, synonyms, and official translations.

Instructions

Get detailed information about a MeSH descriptor by ID.

Use this tool to:

Get the full definition (scope note) of a MeSH term
View tree numbers showing hierarchy location
See related concepts and synonyms

Provide a MeSH Descriptor ID like "D015242" (Ofloxacin). Set language to request NLM's official translations where they exist (e.g. language: "pt").

Input Schema

Name	Required	Description	Default
`mesh_id`	Yes	MeSH Descriptor ID (e.g., D015242, D003920)
`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
`id`	Yes	MeSH descriptor ID (e.g. "D003920").
`uri`	Yes	NLM MeSH RDF URI of the descriptor.
`label`	Yes	Descriptor heading, in the requested language when NLM publishes that translation.
`concepts`	Yes	The preferred concept with its entry terms (synonyms); non-preferred concepts are not retrieved. Empty when the descriptor names no preferred concept.
`provenance`	Yes	Provenance block: source, URL, data vintage, extraction instant, origin diagnostics, citation, license
`qualifiers`	Yes	Allowable qualifiers (subheadings) for the descriptor.
`scope_note`	Yes	Scope note (definition) of the descriptor's preferred concept; empty when it has none.
`attribution`	Yes	Canonical source URLs of this response (attribution list)
`tree_numbers`	Yes	Tree numbers placing the descriptor in the MeSH hierarchy (e.g. "C18.452.394.750").

Schema Changelog

Changes observed during successful MCP inspections.

Changed7 schema fields changedv2.4.0Oct 29, 2026

addedOutput schema / properties / concepts / description

Added value: +"The preferred concept with its entry terms (synonyms); non-preferred concepts are not retrieved. Empty when the descriptor names no preferred concept."

addedOutput schema / properties / id / description

Added value: +"MeSH descriptor ID (e.g. \"D003920\")."

addedOutput schema / properties / label / description

Added value: +"Descriptor heading, in the requested language when NLM publishes that translation."

addedOutput schema / properties / qualifiers / description

Added value: +"Allowable qualifiers (subheadings) for the descriptor."

addedOutput schema / properties / scope_note / description

Added value: +"Scope note (definition) of the descriptor's preferred concept; empty when it has none."

addedOutput schema / properties / tree_numbers / description

Added value: +"Tree numbers placing the descriptor in the MeSH hierarchy (e.g. \"C18.452.394.750\")."

addedOutput schema / properties / uri / description

Added value: +"NLM MeSH RDF URI of the descriptor."

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"
+]
```

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: -[
-  "id",
-  "uri",
-  "label",
-  "scope_note",
-  "tree_numbers",
-  "concepts",
-  "qualifiers"
-]New value: +[
+  "id",
+  "uri",
+  "label",
+  "scope_note",
+  "tree_numbers",
+  "concepts",
+  "qualifiers",
+  "provenance",
+  "attribution"
+]

Changed1 schema field changedv1.5.7Jun 21, 2026
- removedInput schema / additionalProperties
```
Removed value: -false
```

Changed1 schema field changedv1.4.0May 12, 2026

addedInput schema / properties / language

Added value: +{
+  "default": "en",
+  "description": "Language code (default: en)",
+  "enum": [
+    "en",
+    "es",
+    "pt",
+    "fr",
+    "de",
+    "it",
+    "zh",
+    "ja",
+    "ar",
+    "ru"
+  ],
+  "type": "string"
+}

First observedv1.2.1May 11, 2026

TDQS

A3.8/5.0

Behavior3/5

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

Annotations already declare readOnlyHint=true, idempotentHint=true and destructiveHint=false, so the safety profile is fully covered. The description adds that translations are NLM-official and never machine-translated, but that same fact is already stated verbatim in the schema's language property description, so net new behavioral disclosure is thin.

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?

The lead sentence is front-loaded and the bullet list is tight, with no filler or repetition across sentences. The example parentheticals are slightly redundant with the schema but do not bloat the text.

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?

A two-parameter read-only lookup with full schema coverage and an output schema needs little more; the description covers input format, the nature of the returned content, and language behavior. Nothing an agent needs in order to invoke it 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 description coverage is 100% and the regex pattern plus enum already constrain both parameters, so baseline 3 applies. The description's ID example ('D015242' Ofloxacin) and language example duplicate material already present in the schema rather than adding new semantics.

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?

States a specific verb and resource ('Get detailed information about a MeSH descriptor by ID') and enumerates what is returned (scope note, tree numbers, related concepts, synonyms). However, it never names the sibling lookup tools (mesh_search, mesh_tree, mesh_qualifiers) to draw a boundary, so differentiation is left implicit through the 'by ID' framing.

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

Usage Guidelines4/5

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

The 'Use this tool to:' bullets give clear positive contexts (full definition, hierarchy location, synonyms) and the ID example shows the expected input form. It stops short of stating when NOT to use it or naming the alternative (e.g. use mesh_search when you only have a term string).

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