Mcp Package Docs

Package Documentation MCP Server

An MCP (Model Context Protocol) server that provides LLMs with efficient access to package documentation across multiple programming languages and language server protocol (LSP) capabilities.

Note: I am not actively maintaining the codebase at present. While it doesn't provide access to private package documentation - the Context7 MCP server and service meets my needs which are mostly for public package documentation. I personally use Context7 via my mcp-devtools MCP server which is actively maintained.

Features

• Multi-Language Support:
• Go packages via go doc
• Python libraries via built-in help()
• NPM packages via registry documentation (including private registries)
• Rust crates via crates.io and docs.rs

• Smart Documentation Parsing:
• Structured output with description, usage, and examples
• Focused information to avoid context overload
• Support for specific symbol/function lookups
• Fuzzy and exact search capabilities across documentation

• Advanced Search Features:
• Search within package documentation
• Fuzzy matching for flexible queries
• Context-aware results with relevance scoring
• Symbol extraction from search results

• Language Server Protocol (LSP) Support:
• Hover information for code symbols
• Code completions
• Diagnostics (errors and warnings)
• Currently supports TypeScript/JavaScript
• Extensible for other languages

• Performance Optimised:
• Built-in caching
• Efficient parsing
• Minimal memory footprint

Installation

Note: I do not recommend using npx -y to run your MCP servers in production as you're esentially trusting whatever package you're downloading off the internet at that moment in time. I highly recommend cloning the repository locally or building into a container image.

npx -y mcp-package-docs

Usage

As an MCP Server

1. Add to your MCP settings configuration:

{
  "mcpServers": {
    "package-docs": {
      "command": "npx",
      "args": ["-y", "mcp-package-docs"],
      "env": {
        "ENABLE_LSP": "true" // Optional: Enable Language Server Protocol support
      }
    }
  }
}

1. The LSP functionality includes default configurations for common language servers:

• TypeScript/JavaScript: typescript-language-server --stdio
• HTML: vscode-html-language-server --stdio
• CSS: vscode-css-language-server --stdio
• JSON: vscode-json-language-server --stdio

You can override these defaults if needed:

{
  "mcpServers": {
    "package-docs": {
      "command": "npx",
      "args": ["-y", "mcp-package-docs"],
      "env": {
        "ENABLE_LSP": "true",
        "TYPESCRIPT_SERVER": "{\"command\":\"/custom/path/typescript-language-server\",\"args\":[\"--stdio\"]}"
      }
    }
  }
}

1. The server provides the following tools:

lookupgodoc / describegopackage

Fetches Go package documentation

{
  "name": "describe_go_package",
  "arguments": {
    "package": "encoding/json", // required
    "symbol": "Marshal"        // optional
  }
}

lookuppythondoc / describepythonpackage

Fetches Python package documentation

{
  "name": "describe_python_package",
  "arguments": {
    "package": "requests",    // required
    "symbol": "get"          // optional
  }
}

describerustpackage

Fetches Rust crate documentation from crates.io and docs.rs

{
  "name": "describe_rust_package",
  "arguments": {
    "package": "serde",      // required: crate name
    "version": "1.0.219"     // optional: specific version
  }
}

searchpackagedocs

Search within package documentation

{
  "name": "search_package_docs",
  "arguments": {
    "package": "requests",    // required: package name
    "query": "authentication", // required: search query
    "language": "python",     // required: "go", "python", "npm", "swift", or "rust"
    "fuzzy": true            // optional: enable fuzzy matching (default: true)
  }
}

lookupnpmdoc / describenpmpackage

Fetches NPM package documentation from both public and private registries. Automatically uses the appropriate registry based on your .npmrc configuration.

{
  "name": "describe_npm_package",
  "arguments": {
    "package": "axios",      // required - supports both scoped (@org/pkg) and unscoped packages
    "version": "1.6.0"       // optional
  }
}

The tool reads your ~/.npmrc file to determine the correct registry for each package:

• Uses scoped registry configurations (e.g., @mycompany:registry=...)
• Supports private registries (GitHub Packages, GitLab, Nexus, Artifactory, etc.)
• Falls back to the default npm registry if no custom registry is configured

Example .npmrc configurations:

registry=https://nexus.mycompany.com/repository/npm-group/
@mycompany:registry=https://nexus.mycompany.com/repository/npm-private/
@mycompany-ct:registry=https://npm.pkg.github.com/

Language Server Protocol (LSP) Tools

When LSP support is enabled, the following additional tools become available:

get_hover

Get hover information for a position in a document

{
  "name": "get_hover",
  "arguments": {
    "languageId": "typescript", // required: language identifier (e.g., "typescript", "javascript")
    "filePath": "src/index.ts", // required: path to the source file
    "content": "const x = 1;",  // required: content of the file
    "line": 0,                  // required: zero-based line number
    "character": 6,             // required: zero-based character position
    "projectRoot": "/path/to/project" // optional: project root directory
  }
}

get_completions

Get completion suggestions for a position in a document

{
  "name": "get_completions",
  "arguments": {
    "languageId": "typescript", // required: language identifier
    "filePath": "src/index.ts", // required: path to the source file
    "content": "const arr = []; arr.",  // required: content of the file
    "line": 0,                  // required: zero-based line number
    "character": 16,            // required: zero-based character position
    "projectRoot": "/path/to/project" // optional: project root directory
  }
}

get_diagnostics

Get diagnostic information (errors, warnings) for a document

{
  "name": "get_diagnostics",
  "arguments": {
    "languageId": "typescript", // required: language identifier
    "filePath": "src/index.ts", // required: path to the source file
    "content": "const x: string = 1;",  // required: content of the file
    "projectRoot": "/path/to/project" // optional: project root directory
  }
}

Example Usage in an LLM

Looking up Documentation

// Looking up Go documentation
const goDocResult = await use_mcp_tool({
  server_name: "package-docs",
  tool_name: "describe_go_package",
  arguments: {
    package: "encoding/json",
    symbol: "Marshal"
  }
});

// Looking up Python documentation
const pythonDocResult = await use_mcp_tool({
  server_name: "package-docs",
  tool_name: "describe_python_package",
  arguments: {
    package: "requests",
    symbol: "post"
  }
});

// Looking up Rust documentation
const rustDocResult = await use_mcp_tool({
  server_name: "package-docs",
  tool_name: "describe_rust_package",
  arguments: {
    package: "serde"
  }
});

// Searching within documentation
const searchResult = await use_mcp_tool({
  server_name: "package-docs",
  tool_name: "search_package_docs",
  arguments: {
    package: "serde",
    query: "serialize",
    language: "rust",
    fuzzy: true
  }
});

// Using LSP for hover information (when LSP is enabled)
const hoverResult = await use_mcp_tool({
  server_name: "package-docs",
  tool_name: "get_hover",
  arguments: {
    languageId: "typescript",
    filePath: "src/index.ts",
    content: "const axios = require('axios');\naxios.get",
    line: 1,
    character: 7
  }
});

Requirements

• Node.js >= 20
• Go (for Go package documentation)
• Python 3 (for Python package documentation)
• Internet connection (for NPM package documentation and Rust crate documentation)
• Language servers (for LSP functionality):
• TypeScript/JavaScript: npm install -g typescript-language-server typescript
• HTML/CSS/JSON: npm install -g vscode-langservers-extracted

Development

# Install dependencies
npm i

# Build
npm run build

# Watch mode
npm run watch

Contributing

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

License

This project is licensed under the MIT License - see the [LICENSE](LICENSE) file for details.

Source & license

This open-source MCP server is cataloged on AgentStack and links to its original source — we do not rehost the code.

• Author: sammcj
• Source: sammcj/mcp-package-docs
• License: MIT
• Homepage: https://smcleod.net

Install and usage instructions live in the source repository linked above.