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MDN MCP Server

MDN publishes an official MCP server at https://mcp.mdn.mozilla.net/ that gives any MCP-compatible client direct access to MDN's documentation and browser compatibility data. Instead of relying on a model's training-data snapshot, your agent or IDE pulls live, authoritative web platform information at inference time.

The server is experimental but publicly available with no authentication required.

Why it matters​

AI tools trained on a fixed dataset go stale. Browser compatibility tables shift with every release cycle, and new web platform APIs land constantly. Without a live source, a model can confidently recommend a CSS property or JS API that has poor support on a browser your users actually run.

The MDN MCP server solves this by giving your tools a real-time lookup channel:

  • Browser support data grounded in BCD (Browser Compatibility Data), the same dataset powering caniuse
  • Up-to-date documentation — spec changes, deprecations, and new APIs appear as MDN publishes them
  • Faster answers — structured MCP responses are roughly 2× faster than the model reasoning from memory alone

Setup​

The server uses HTTP transport. Add it once; any MCP client that supports remote HTTP servers can use the same URL.

Claude Code​

claude mcp add --transport http mdn https://mcp.mdn.mozilla.net/

This stores the server in your Claude Code config. Confirm it's active with claude mcp list.

VS Code (GitHub Copilot / MCP extension)​

Add to .vscode/mcp.json in your project, or to your user settings.json:

{
    "servers": {
        "mdn": {
            "type": "http",
            "url": "https://mcp.mdn.mozilla.net/"
        }
    }
}

See the VS Code MCP docs for the full settings path.

Cursor​

Add to .cursor/mcp.json:

{
    "mcpServers": {
        "mdn": {
            "url": "https://mcp.mdn.mozilla.net/"
        }
    }
}

See the Cursor MCP docs for project vs global scope.

Zed​

Add to your Zed settings under context_servers:

{
    "context_servers": {
        "mdn": {
            "source": {
                "type": "url",
                "url": "https://mcp.mdn.mozilla.net/"
            }
        }
    }
}

See the Zed MCP docs for details.

Claude Desktop​

Add to your Claude Desktop config file (claude_desktop_config.json):

{
    "mcpServers": {
        "mdn": {
            "type": "http",
            "url": "https://mcp.mdn.mozilla.net/"
        }
    }
}

See the Claude Desktop connector docs for the config file location.

What the server exposes​

The MDN MCP server is a read-only data source — it does not execute code or modify anything. Tools exposed typically include:

  • Browser compatibility lookup — given a feature name, returns a BCD-backed support table across browsers and versions
  • MDN documentation fetch — returns structured content from a specific MDN page
  • Feature search — find MDN pages and API entries by keyword

The exact tool list evolves as MDN expands the server; check the mdn/mcp repository for the current spec.

Privacy​

Queries sent to the MDN MCP server are processed by Mozilla's infrastructure. Review MDN's data retention and privacy notes at https://developer.mozilla.org/en-US/mcp#privacy_and_data_retention before using it in contexts where query confidentiality matters (e.g. internal codebases with proprietary feature names).

See also​