godoc-mcp

Overview

godoc-mcp is a Model Context Protocol (MCP) server that provides efficient access to Go documentation. It helps LLMs understand Go projects by providing direct access to package documentation without needing to read entire source files. godoc-mcp can vastly improve the performance of using LLMs to develop in Go by substantially reducing the number of tokens needed to understand and make use of Go packages.

Getting Started

go install github.com/mrjoshuak/godoc-mcp@latest

Why Use godoc-mcp?

In a sentence: godoc-mcp provides a more token efficient way for LLMs to understand Go projects.

Traditional file-reading approaches require LLMs to process entire source files often many files to understand a single package. godoc-mcp provides several advantages:

1. Token Efficiency: Returns only the essential documentation, reducing token usage significantly
2. Structured Information: Provides official package documentation in a consistent, well-structured format
3. Project Navigation: Smart handling of project structures helps LLMs understand multi-package projects
4. Integration Ready: Works alongside other MCP servers, enabling both high-level and detailed code analysis
5. Performance: Caching and optimized token usage make godoc-mcp a fast and efficient tool for Go development
6. Local: Does not require an internet connection to access documentation

With godoc-mcp, a LLM can get precisely the information it needs without having to read entire source files. Here are the different levels of detail that an LLM can get.

• Documentation for one exported symbol
• The complete source for one symbol
• A list of all exported symbols (the concise documentation)
• A list of all symbols including unexported symbols
• The full documentation for a package
• The entire source for a package

This makes godoc-mcp an essential tool for Go developers using LLMs by enabling LLMs to understand significantly more, and in more detail, about the context than previously possible in any programming language.

Features

The server will:

1. For directories with Go files: Return package documentation
2. For directories without Go files: List available Go packages in subdirectories
3. For import paths: Return standard library or third-party package documentation

• Efficient Documentation Access: Retrieves official Go documentation with minimal token usage
• Smart Package Discovery: When pointed at a directory without Go files, lists available Go packages in subdirectories
• Flexible Path Support:
  • Local file paths (e.g., "/full/path/to/mypackage")
  • Import paths (e.g., "io", "github.com/user/repo")
• Automatic Module Context:
  • Creates temporary Go projects when needed
  • Automatically sets up module context for external packages
  • No manual module setup required for any package documentation
  • Handles cleanup of temporary projects
• Module-Aware: Supports documentation for third-party packages through working directory context (i.e. it will run go doc from the working directory)
• Performance Optimized:
  • Built-in response caching
  • Efficient token usage through focused documentation retrieval
  • Metadata about response sizes
  • Smart handling of standard library vs external packages

Examples

In addition to providing documentation while working on coding tasks. godoc-mcp can also be used to explore Go projects and packages. Here are some examples for general prompting:

Project Understanding

"I'm looking at a Go project at /path/to/some/project. What packages does it contain and what do they do?"

Package Interface Understanding

"What interfaces does the io package provide? I'm particularly interested in anything related to reading."

Implementation Guidance

"I need to implement the io.Reader interface. Show me its documentation and any related types I should know about."

API Usage

"Show me the documentation for the Resource type in the /path/to/some/project. I need to understand how to create and use it."

Library Exploration

"I'm in /path/to/some/project which uses github.com/gorilla/mux. Show me the documentation for the Router type."

Method Discovery

"What methods are available on the http.Request type? I'm working with standard library HTTP handlers."

Focused Learning

"Explain how to configure the Server type in the /path/to/project/server package."

Package Browsing

"I'm in a new Go project directory and see multiple packages. Can you show me what each one does?"

Usage

Transport Options

godoc-mcp supports three transport modes:

• stdio (default): Standard input/output, for local MCP clients like Claude Desktop
• sse: Server-Sent Events over HTTP, for web-based MCP clients
• http: Streamable HTTP, the MCP specification's recommended HTTP transport

# Default stdio mode
godoc-mcp

# SSE mode on port 8080
godoc-mcp --transport sse --addr :8080

# Streamable HTTP mode
godoc-mcp --transport http --addr :9090

Docker

docker pull ghcr.io/mrjoshuak/godoc-mcp:latest

For use with Docker MCP Gateway, add to your MCP configuration:

{
  "mcpServers": {
    "godoc": {
      "command": "docker",
      "args": ["run", "-i", "--rm", "ghcr.io/mrjoshuak/godoc-mcp:latest"]
    }
  }
}

To access local project documentation, mount your project directory and use /workspace as the working_dir parameter:

{
  "mcpServers": {
    "godoc": {
      "command": "docker",
      "args": ["run", "-i", "--rm", "-v", "/path/to/project:/workspace", "ghcr.io/mrjoshuak/godoc-mcp:latest"]
    }
  }
}

To run with SSE transport via Docker:

docker run --rm -p 8080:8080 ghcr.io/mrjoshuak/godoc-mcp:latest --transport sse --addr :8080

Claude Code

claude mcp add godoc-mcp -- godoc-mcp

Claude Desktop

To add to the Claude desktop app, edit your MCP config:

{
  "mcpServers": {
    "godoc": {
      "command": "godoc-mcp"
    }
  }
}

If go doc can't find your Go installation, add environment variables:

{
  "mcpServers": {
    "godoc": {
      "command": "godoc-mcp",
      "env": {
        "GOPATH": "/path/to/go",
        "GOMODCACHE": "/path/to/go/pkg/mod"
      }
    }
  }
}

Tool Parameters

When connected to an MCP-capable LLM (like Claude), godoc-mcp provides the get_doc tool with the following parameters:

• path (required): Path to the Go package or file (import path or file path)
• target (optional): Specific symbol to document (function, type, etc.)
• cmd_flags (optional): Additional go doc command flags (allowed: -all, -src, -u, -short, -c)
• working_dir (optional): Working directory for module-aware documentation (if not provided, a temporary project will be created automatically)
• page (optional): Page number for paginated results (default: 1)
• page_size (optional): Lines per page, 100-5000 (default: 1000)

Troubleshooting

• For local paths, ensure they contain Go source files or point to directories containing Go packages
• If you see module-related errors, ensure GOPATH and GOMODCACHE environment variables are set correctly in your MCP server configuration
• The server automatically handles module context for external packages, but you can still provide a specific working_dir if needed for special cases

License

This project is licensed under the MIT License - see the LICENSE file for details.