Best for
- Web developers who need accurate, current web platform documentation
- Coding agents aiming to reduce inaccuracies caused by outdated LLM training data
M
MDN MCP Server
Official
MDN's official experimental MCP server for web search, docs, and browser compatibility data
GitHub source repository ↗
53FMRS · D
The MDN MCP server is an official Mozilla-maintained experimental project giving coding agents authoritative, current web platform docs and compatibility data, but it currently discloses limited details (no public tool list) and is explicitly labeled experimental, subject to change or withdrawal at any time.
The MDN MCP server is an experimental server maintained by Mozilla's MDN team that exposes MDN's search, documentation, and browser compatibility data to LLMs and coding agents. The goal is to give these tools a reliable, up-to-date source of web platform documentation instead of relying on potentially outdated training data. The repository lives at mdn/mcp under the MPL-2.0 license; the README does not list specific tool names or parameters, so the exact tool set cannot be confirmed from the available source.
Tools
The tool list has not been reviewed yet.
Setup
Remote: add Mozilla's hosted remote server to your tool, e.g. in Claude Code run claude mcp add --transport http mdn https://mcp.mdn.mozilla.net/. Local: run npm install to install dependencies, then npm start to launch the server, and add the local endpoint, e.g. claude mcp add --transport http mdn-local http://localhost:3002/. For local development, npm run dev starts the dev server, MCP inspector, and tests together.
Fit and risk
Not for
- Users who require strict data-privacy guarantees and want no query logging whatsoever
- Production workflows requiring a stable, guaranteed-uptime API, since this server is experimental and may be withdrawn at any time
Required permissions
- The server itself does not require access to local files or a codebase
- Using the remote server sends query content to Mozilla's servers
Risks and side effects
- The README states that query data is stored for analytics; it is not linked to identifying user information, but private details a user shares with the LLM could inadvertently be included in logged queries
- As an experimental project, the server may be withdrawn at any time, making it unsuitable for dependencies requiring long-term stability
- Use of the remote server requires compliance with Mozilla's Acceptable Use Policy
Troubleshooting
- Send the `X-Moz-1st-Party-Data-Opt-Out: 1` header to opt out of first-party analytics
- For local runs, confirm `npm install` completed and the default port (3002) is free
- Verify the client is configured with http transport and the correct endpoint (remote or local URL)
Use cases
Querying MDN documentation for Web APIs, HTML/CSS/JS from within a coding assistant
Checking browser compatibility data for a given web feature
Letting a coding agent verify whether a platform feature is still valid or deprecated before generating code
Supported clients
Claude CodeFull support