Medical Terminologies MCP

Search MeSH

mesh_search

Read-onlyIdempotent

Search for MeSH (Medical Subject Headings) descriptors.

Use this tool to:

Find MeSH terms for indexing medical literature
Look up subject headings for PubMed searches
Find controlled vocabulary terms

Set language to request NLM's official translations where they exist (e.g. language: "pt" for Portuguese labels); content is never machine-translated.

Returns matching descriptors with MeSH IDs and labels.

Input Schema

TableJSON Schema

Name	Required	Description	Default
`match`	No	Match type: exact, contains, or startswith. Default: contains	contains
`query`	Yes	Search term (e.g., "diabetes", "heart failure")
`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
`max_results`	No	Maximum number of results (1-100). Default: 25

Output Schema

TableJSON Schema

Name	Required	Description
`match`	Yes
`query`	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)
`descriptors`	Yes
`total_count`	Yes

Schema Changelog

Changes observed during successful MCP inspections.

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

A3.9/5.0

Behavior4/5

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

Annotations already cover read-only/idempotent/open-world, so the bar is lower; the description adds a real behavioral fact beyond them – that language returns NLM's official translations and content is never machine-translated. It also states the return shape (descriptors with MeSH IDs and labels).

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 purpose sentence followed by a compact bullet list and a single sentence on language behavior and return values. Efficient overall, with only minor overlap between the prose language note and the identical schema text.

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

Completeness4/5

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

For a search tool whose annotations cover the safety profile and whose output schema exists, the definition supplies purpose, use cases, the non-obvious translation caveat, and the return shape. Nothing critical to correct invocation 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%, including the match enum, language enum, and max_results bounds, so the baseline is 3. The description's language explanation with a 'pt' example largely restates what the schema already documents, adding little beyond it.

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+resource ("Search for MeSH descriptors") and enumerates concrete use cases (indexing, PubMed subject headings, controlled vocabulary), which clearly separate it from lookup siblings like mesh_descriptor. It never names a sibling explicitly, so differentiation is functional rather than direct.

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" list gives clear retrieval contexts (indexing terms, PubMed subject headings, controlled vocabulary), so when-to-use is well established. It stops short of exclusions or naming alternatives such as mesh_descriptor or mesh_tree for ID/tree navigation.

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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