Medical Terminologies MCP Server

A Model Context Protocol (MCP) server providing unified access to major global medical terminologies:

• ICD-11 - International Classification of Diseases (WHO)
• SNOMED CT - Systematized Nomenclature of Medicine
• LOINC - Logical Observation Identifiers Names and Codes
• RxNorm - Normalized names for clinical drugs (NIH)
• MeSH - Medical Subject Headings (NLM)

Features

• 27 specialized tools for medical terminology lookup
• Multi-terminology support in a single server
• Cross-terminology mapping and search
• Built-in caching for improved performance
• Rate limiting to respect API limits
• Detailed responses with rich formatting

Installation

Global Installation (Recommended)

npm install -g medical-terminologies-mcp

Local Installation

npm install medical-terminologies-mcp

Configuration

Claude Desktop

Add to your Claude Desktop configuration file:

macOS: ~/Library/Application Support/Claude/claude_desktop_config.json Windows: %APPDATA%\Claude\claude_desktop_config.json

{
  "mcpServers": {
    "medical-terminologies": {
      "command": "npx",
      "args": ["-y", "medical-terminologies-mcp"],
      "env": {
        "WHO_CLIENT_ID": "your-who-client-id",
        "WHO_CLIENT_SECRET": "your-who-client-secret"
      }
    }
  }
}

Environment Variables

¹ Required for ICD-11 tools. Get credentials at: https://icd.who.int/icdapi.

² See SNOMED CT setup (advanced) below. LOINC, RxNorm, and MeSH need no configuration.

Available Tools (21 by default, 27 with SNOMED enabled)

ICD-11 Tools (5)

LOINC Tools (4)

RxNorm Tools (5)

MeSH Tools (4)

SNOMED CT Tools (5, disabled by default)

These are only registered when ENABLE_SNOMED_TOOLS=true. See SNOMED CT setup (advanced).

Crosswalk Tools (4 — map_snomed_to_icd10 requires SNOMED)

Usage Examples

Search for a diagnosis in ICD-11

Use icd11_search with query "type 2 diabetes mellitus"

Look up a lab test in LOINC

Use loinc_details with loinc_num "2339-0" to get glucose test details

Find drug information in RxNorm

Use rxnorm_search with query "metformin" then rxnorm_concept for details

Search across all terminologies

Use find_equivalent with term "diabetes" to search ICD-11, SNOMED, LOINC, RxNorm, and MeSH

Map ICD-10 to ICD-11

Use map_icd10_to_icd11 with icd10_code "E11" to find ICD-11 equivalents

SNOMED CT setup (advanced)

The 5 SNOMED tools (snomed_search, snomed_concept, snomed_hierarchy, snomed_descriptions, snomed_ecl) plus the SNOMED-dependent crosswalk tool (map_snomed_to_icd10) are disabled by default. With them disabled, the server registers 21 tools instead of 27; find_equivalent still works and skips the SNOMED branch with an explanatory note.

The reason: as of 2026-05-08, the public IHTSDO Snowstorm endpoint that this project historically called (https://browser.ihtsdotools.org/snowstorm/snomed-ct/...) returns HTTP 410 Gone for every path. Without a working backend, registering these tools surfaces 6 guaranteed-broken tools to every client.

To enable the SNOMED tools:

1. Confirm your SNOMED CT license. SNOMED CT use requires an SNOMED International (IHTSDO) license. Member country residents typically have one through their national release center; non-members can obtain an Affiliate license. See https://www.snomed.org/snomed-ct/get-snomed.

2. Run a Snowstorm instance. SNOMED International publishes Snowstorm as open source (IHTSDO/snowstorm) and as a Docker image (snomedinternational/snowstorm). Self-hosting requires importing an RF2 release file (provided to license holders).

3. Configure this server:

   {
     "mcpServers": {
       "medical-terminologies": {
         "command": "npx",
         "args": ["-y", "medical-terminologies-mcp"],
         "env": {
           "WHO_CLIENT_ID": "...",
           "WHO_CLIENT_SECRET": "...",
           "ENABLE_SNOMED_TOOLS": "true",
           "SNOMED_BASE_URL": "https://my-snowstorm.example.com/snowstorm/snomed-ct",
           "SNOMED_LANGUAGE": "en"
         }
       }
     }
   }
   

   SNOMED_BASE_URL should point at the base under which Snowstorm exposes its /MAIN/concepts and related endpoints. SNOMED_LANGUAGE accepts standard Accept-Language tags (e.g. pt, es, pt-BR,en;q=0.8) — Snowstorm returns localized terms when the branch has them and falls back to English otherwise.

4. Restart the MCP client so the server picks up the env vars.

If you set ENABLE_SNOMED_TOOLS=true without configuring a working Snowstorm, the SNOMED tools will register but every call will fail at the network layer.

Terminology Licenses

ICD-11 (WHO)

ICD-11 content is provided under the Creative Commons Attribution-NoDerivatives 3.0 IGO license (CC BY-ND 3.0 IGO).

• You must attribute WHO as the source
• You may not create derivative works
• API access requires registration at https://icd.who.int/icdapi

SNOMED CT

SNOMED CT use requires an IHTSDO (SNOMED International) license. The SNOMED tools in this server are disabled by default and only enabled by operators with a valid license and a self-hosted Snowstorm instance — see SNOMED CT setup (advanced).

• Member countries have national licenses
• Affiliate licenses available for others
• More info: https://www.snomed.org/snomed-ct/get-snomed

LOINC

LOINC content is provided under the LOINC License.

• Free for most uses
• Attribution required
• Registration recommended

RxNorm

RxNorm is produced by the U.S. National Library of Medicine and is freely available.

• No license required for use
• Attribution appreciated

MeSH

MeSH is produced by the U.S. National Library of Medicine and is freely available.

• No license required for use
• Attribution appreciated

API Rate Limits

This server implements rate limiting to respect API providers:

Development

Building from source

git clone https://github.com/SidneyBissoli/medical-terminologies-mcp.git
cd medical-terminologies-mcp
npm install
npm run build

Running locally

npm start

Testing with MCP Inspector

npx @modelcontextprotocol/inspector node dist/index.js

Contributing

Contributions are welcome! Please feel free to submit a Pull Request.

1. Fork the repository
2. Create your feature branch (git checkout -b feature/AmazingFeature)
3. Commit your changes (git commit -m 'Add some AmazingFeature')
4. Push to the branch (git push origin feature/AmazingFeature)
5. Open a Pull Request

Author

Sidney Bissoli

• GitHub: @SidneyBissoli

License

This project is licensed under the MIT License - see the LICENSE file for details.

Note: While this software is MIT licensed, the medical terminologies accessed through it have their own licenses (see Terminology Licenses above).

Acknowledgments

• WHO for the ICD-11 API
• Regenstrief Institute for LOINC
• U.S. National Library of Medicine for RxNorm and MeSH
• SNOMED International for SNOMED CT
• Anthropic for the Model Context Protocol

Support

If you encounter any issues or have questions:

• Open an issue on GitHub
• Check existing issues for solutions

Made with love for the medical informatics community