mdn-mcp

MCP server for MDN Web Docs — search documentation, fetch pages, and check browser compatibility right from your AI assistant.

Features

| Tool | Description | Data Source | |------|-------------|-------------| | mdn_search | Search MDN by keyword | MDN Search API (remote) | | mdn_doc | Fetch full documentation for a page | MDN JSON API (remote) | | mdn_compat | Browser compatibility check | @mdn/browser-compat-data (offline) | | mdn_list | Browse & discover BCD features by namespace | @mdn/browser-compat-data (offline) | | mdn_css | CSS property formal definitions | mdn-data (offline) | | mdn_http | HTTP headers, status codes, methods reference | @mdn/browser-compat-data (offline) |

Setup

No installation needed — just configure your MCP client:

Add to .vscode/mcp.json:

{
  "servers": {
    "mdn": {
      "command": "npx",
      "args": ["-y", "mdn-mcp"]
    }
  }
}

Add to .cursor/mcp.json:

{
  "mcpServers": {
    "mdn": {
      "command": "npx",
      "args": ["-y", "mdn-mcp"]
    }
  }
}

Add to ~/.codeium/windsurf/mcp_config.json:

{
  "mcpServers": {
    "mdn": {
      "command": "npx",
      "args": ["-y", "mdn-mcp"]
    }
  }
}

Add to claude_desktop_config.json:

{
  "mcpServers": {
    "mdn": {
      "command": "npx",
      "args": ["-y", "mdn-mcp"]
    }
  }
}

claude mcp add --transport stdio mdn -- npx -y mdn-mcp

Or add to .mcp.json (shared with team):

{
  "mcpServers": {
    "mdn": {
      "command": "npx",
      "args": ["-y", "mdn-mcp"]
    }
  }
}

Add to settings.json:

{
  "context_servers": {
    "mdn": {
      "command": "npx",
      "args": ["-y", "mdn-mcp"]
    }
  }
}

Open Settings → Tools → AI Assistant → MCP, click +, and paste:

{
  "mcpServers": {
    "mdn": {
      "command": "npx",
      "args": ["-y", "mdn-mcp"]
    }
  }
}

gemini mcp add mdn -- npx -y mdn-mcp

Or add to ~/.gemini/settings.json:

{
  "mcpServers": {
    "mdn": {
      "command": "npx",
      "args": ["-y", "mdn-mcp"]
    }
  }
}

Any MCP client that supports stdio transport can use this server. The command is:

npx -y mdn-mcp

See the full list of MCP clients.

Local development

git clone https://github.com/anvme/mdn-mcp.git
cd mdn-mcp
npm install
node index.js

Tool Reference

mdn_search

Search MDN Web Docs by keyword.

| Parameter | Type | Required | Default | Description | |-----------|------|----------|---------|-------------| | query | string | yes | — | Search query | | limit | number | no | 5 | Max results (1–20) |

Example: { "query": "Array.map", "limit": 3 }

mdn_doc

Fetch full documentation for a specific MDN page. Supports pagination for large pages.

| Parameter | Type | Required | Default | Description | |-----------|------|----------|---------|-------------| | path | string | yes | — | MDN doc path or full URL | | sections | string[] | no | — | Filter sections: syntax, description, parameters, return_value, examples, see_also | | max_length | number | no | 5000 | Max characters to return (500–50000) | | start_index | number | no | 0 | Character offset for pagination |

Example: { "path": "Web/CSS/grid", "sections": ["syntax", "description"] }

mdn_compat

Check browser compatibility for a web feature. Works offline.

| Parameter | Type | Required | Description | |-----------|------|----------|-------------| | feature | string | yes | BCD feature path, e.g. css.properties.grid, api.fetch, javascript.builtins.Array.map |

Example: { "feature": "javascript.builtins.Array.map" }

Returns a Markdown table with version support for Chrome, Edge, Firefox, Safari, Opera, iOS Safari, Chrome Android, Firefox Android, Node.js, Deno, and Bun.

mdn_list

Browse and discover BCD features by namespace. Filter by keyword or status.

| Parameter | Type | Required | Default | Description | |-----------|------|----------|---------|-------------| | path | string | no | "" | BCD path to browse, e.g. css.properties, api, javascript.builtins | | query | string | no | — | Filter features by keyword | | deprecated | boolean | no | — | true = only deprecated, false = exclude deprecated | | experimental | boolean | no | — | true = only experimental, false = exclude experimental | | limit | number | no | 50 | Max features to return (1–200) |

Examples:

• { "path": "css.properties", "query": "grid" } — find CSS grid-related properties
• { "path": "api", "deprecated": true, "limit": 20 } — list deprecated Web APIs
• { "path": "" } — show all top-level BCD namespaces

mdn_css

Get CSS property formal definitions — syntax, initial value, inheritance, computed value, animation type, and more. Works offline.

| Parameter | Type | Required | Description | |-----------|------|----------|-------------| | name | string | yes | CSS property, function, at-rule, selector, type, or unit name |

Examples:

• { "name": "grid" } — full grid shorthand definition
• { "name": "display" } — display property formal syntax
• { "name": ":hover" } — :hover selector info
• { "name": "calc" } — calc() function info

mdn_http

Browse HTTP reference data — headers, status codes, methods, with browser compatibility.

| Parameter | Type | Required | Default | Description | |-----------|------|----------|---------|-------------| | topic | string | no | "" | HTTP topic path, e.g. headers, headers.Content-Type, status.200 |

Examples:

• { "topic": "" } — list all HTTP categories
• { "topic": "headers" } — list all HTTP headers
• { "topic": "headers.Content-Type" } — browser compat for Content-Type
• { "topic": "status" } — list all HTTP status codes

Prerequisites

• Node.js >= 18

License

MIT