MCP Rust Documentation Server

This is a Model Context Protocol (MCP) server that provides comprehensive access to Rust crate documentation and metadata, offering essential context for LLMs when working with Rust code.

Features

• Documentation Lookup: Fetches documentation for any Rust crate available on docs.rs
• Crate Search: Search for crates on crates.io with detailed results
• Metadata Retrieval: Get comprehensive metadata for specific crates
• Pagination Support: Handle large documentation with pagination
• Error Handling: Robust error handling with detailed logging
• Session Tracking: Session management for better debugging
• Structured Responses: Well-formatted, structured responses

Architecture

The server follows a modular architecture inspired by AWS MCP server patterns:

mcp-rust-docs/
├── index.js          # Entry point (backward compatibility)
├── src/
│   ├── server.js      # Main server implementation with tools
│   ├── models.js      # Data models and validation schemas
│   └── utils.js       # Utility functions and API clients
├── package.json
└── README.md

Tools Available

1. lookup_crate_docs

Fetches and returns documentation for a specific Rust crate from docs.rs.

Parameters:

• crateName (required): Name of the Rust crate
• version (optional): Specific version (defaults to 'latest')
• maxLength (optional): Maximum characters to return (default: 8000)
• startIndex (optional): Starting character index for pagination (default: 0)

Example Usage:

// Basic lookup
lookup_crate_docs({ crateName: "tokio" })

// Specific version with pagination
lookup_crate_docs({ 
  crateName: "serde", 
  version: "1.0.0",
  maxLength: 5000,
  startIndex: 0 
})

2. search_crates

Search for Rust crates on crates.io with comprehensive results.

Parameters:

• query (required): Search query string
• limit (optional): Maximum results to return (1-50, default: 10)

Example Usage:

search_crates({ query: "web framework", limit: 5 })

3. get_crate_metadata

Get detailed metadata for a specific Rust crate from crates.io.

Parameters:

• crateName (required): Name of the Rust crate

Example Usage:

get_crate_metadata({ crateName: "axum" })

Installation

# Clone the repository
git clone https://github.com/0xKoda/mcp-rust-docs.git
cd mcp-rust-docs

# Install dependencies
npm install

Prerequisites

• Node.js >= 16.0.0
• npm

Usage

# Start the server
npm start

# Development mode with debugging
npm run dev

# Run tests
npm test

Integrating with AI Assistants

Claude Desktop

Add the following to your Claude Desktop configuration file (claude_desktop_config.json):

{
  "mcpServers": {
    "rust-docs": {
      "command": "node",
      "args": ["/absolute/path/to/index.js"]
    }
  }
}

Amazon Q CLI

The server is compatible with Amazon Q CLI's MCP integration. Configure it in your Q CLI settings.

Example Usage Scenarios

Once the server is running and configured with your AI assistant, you can ask questions like:

Documentation Lookup

• "Look up the documentation for the 'tokio' crate"
• "Show me the documentation for 'serde' version 1.0.0"
• "Get the first 5000 characters of 'axum' documentation"

Crate Search

• "Search for web framework crates"
• "Find crates related to async programming"
• "Show me the top 5 HTTP client crates"

Metadata Queries

• "Get metadata for the 'reqwest' crate"
• "What's the latest version of 'clap'?"
• "Show me the download statistics for 'rand'"

Advanced Queries

• "Compare the documentation of 'tokio' and 'async-std'"
• "What are the main features of the 'ratatui' crate?"
• "Find alternatives to the 'hyper' crate"

Key Improvements Over Original

This implementation applies patterns from the AWS Documentation MCP Server:

1. Modular Architecture

• Separated concerns into models, utilities, and server logic
• Better maintainability and testability

2. Enhanced Error Handling

• Comprehensive error handling with detailed messages
• Proper HTTP status code handling
• Graceful degradation for network issues

3. Multiple Tools

• lookup_crate_docs: Documentation fetching
• search_crates: Crate discovery
• get_crate_metadata: Detailed crate information

4. Better Validation

• Strong input validation using Zod schemas
• Parameter bounds checking
• Type safety throughout

5. Session Management

• Session IDs for tracking and debugging
• Better logging with session context

6. Pagination Support

• Handle large documentation with startIndex and maxLength
• Continuation indicators for truncated content

7. Structured Responses

• Consistent response formatting
• Rich metadata in responses
• Better error reporting

Testing with MCP Inspector

You can test this server using the MCP Inspector:

npx @modelcontextprotocol/inspector

Then select "Connect to a local server" and follow the prompts.

API Endpoints Used

• docs.rs: https://docs.rs/{crate}/{version}/{crate}/index.html
• crates.io Search: https://crates.io/api/v1/crates?q={query}
• crates.io Metadata: https://crates.io/api/v1/crates/{crate}

Configuration

The server can be configured through environment variables:

• RUST_DOCS_LOG_LEVEL: Set logging level (default: 'info')
• RUST_DOCS_MAX_CONTENT_LENGTH: Maximum content length (default: 50000)
• RUST_DOCS_REQUEST_TIMEOUT: Request timeout in ms (default: 30000)

Contributing

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

Development Setup

# Install dependencies
npm install

# Run in development mode
npm run dev

# Run tests
npm test

# Lint code
npm run lint

License

MIT

Changelog

v2.0.0

• Complete rewrite with modular architecture
• Added crate search functionality
• Added metadata retrieval
• Enhanced error handling and logging
• Added pagination support
• Improved documentation and examples

v1.0.0

• Initial release with basic documentation lookup