mcp-language-server

Overview

The mcp-language-server is a MCP server that exposes language server protocol (LSP) functionality to LLM clients through the Model Context Protocol. It allows AI models to access semantic code analysis tools including symbol definitions, references, diagnostics, hover information, and renaming capabilities across multiple programming languages including Go, Rust, Python, TypeScript, and C++. The implementation handles LSP communication via stdio and passes environment variables and arguments to language servers.

Try asking AI

After installing, here are 5 things you can ask your AI assistant:

• definition

  Retrieves the complete source code definition of any symbol from your codebase.

  Try:Show me the definition of this functionTry:What is the type definition for this variable
• references

  Locates all usages and references of a symbol throughout the codebase.

  Try:Find all references to this functionTry:Where is this class used
• diagnostics

  Provides diagnostic information for a specific file, including warnings and errors.

  Try:Show me errors in this fileTry:Check diagnostics for current document
• hover

  Display documentation, type hints, or other hover information for a given location.

  Try:Show documentation for this symbolTry:What's the type of this variable
• rename_symbol

  Rename a symbol across a project.

  Try:Rename this function to calculateSumTry:Change the class name from OldClass to NewClass
• edit_file

  Allows making multiple text edits to a file based on line numbers.

  Try:Replace this function with a new implementationTry:Add error handling to this method

Comparable tools

Installation

{
  "mcpServers": {
    "language-server": {
      "command": "mcp-language-server",
      "args": ["--workspace", "/path/to/your/project", "--lsp", "gopls"]
    }
  }
}

FAQ

Which language servers are supported?

The server has been tested with gopls (Go), rust-analyzer (Rust), pyright (Python), typescript-language-server (TypeScript), and clangd (C/C++). It should work with any LSP server that communicates over stdio.

How do I debug issues?

Set the LOG_LEVEL environment variable to DEBUG to enable verbose logging to stderr for all components, including messages to and from the language server.

On Hacker News

Recent discussion from the developer community.

• Show HN: Language Server MCP Server Written in Go▲ 3
  Story by isaacphi · 2025-05-16
• MCP Language Server▲ 2
  Story by wseqyrku · 2025-03-25

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