Isaacphi MCP Language Server

🚀 MCP Language Server

A Model Context Protocol (MCP) server that runs a language server and provides tools to communicate with it.

🚀 Quick Start

This MCP server is designed to bring the power of language servers to large - scale projects, enabling seamless interaction with LLMs.

✨ Features

Motivation

Claude Desktop paired with the filesystem server feels like magic when used on small projects. However, as you add more files and imports, the experience starts to break down. Through this project, I aim to bring this experience to large - scale projects.

Language servers excel at tasks where LLMs often struggle, such as precisely understanding types, relationships, and providing accurate symbol references. This project aims to bring these tools to LLMs. Since the Language Server Protocol (LSP) seems to be an obvious inspiration for MCP, why not combine them?

Status

⚠️ Pre - Beta Quality ⚠️

I've tested this server with the following language servers:

• pyright (Python)
• tsserver (TypeScript)
• gopls (Go)
• rust - analyzer (Rust)

But it should be compatible with many other language servers.

Tools

• read_definition: Retrieve the full source code definition of any symbol (functions, types, constants, etc.).
• find_references: Locate all uses and references of a symbol in the codebase.
• get_diagnostics: Provide diagnostic information, including warnings and errors, for a specific file.
• get_codelens: Retrieve code summary hints for more context and code actions.
• execute_codelens: Run code summary actions.
• apply_text_edit: Allow multiple text edits to a file.

Under the hood, this MCP server can handle the workspace/applyEdit requests of language servers, so it can perform operations such as requesting refactoring, adding imports, and formatting code.

Each tool supports various options to customize the output, such as including line numbers or additional context. Refer to the tool documentation for details. Line numbers are necessary for apply_text_edit to perform accurate edits.

📦 Installation

Prerequisites

Install Go: Follow the instructions at https://golang.org/doc/install

Get or update this server:

go install github.com/isaacphi/mcp - language - server@latest

Install a language server for your codebase:

• Python (pyright): npm install -g pyright
• TypeScript (tsserver): npm install -g typescript typescript - language - server
• Go (gopls): go install golang.org/x/tools/gopls@latest
• Rust (rust - analyzer): rustup component add rust - analyzer
• Or use any other language server

💻 Usage Examples

Setup

Add a configuration like the following to your Claude Desktop settings (or other MCP - supported clients):

{
  "mcpServers": {
    "language - server": {
      "command": "go",
      "args": [
        "run",
        "github.com/isaacphi/mcp - language - server@latest",
        "--workspace",
        "/Users/you/dev/yourpythoncodebase",
        "--lsp",
        "/opt/homebrew/bin/pyright",
        "--",
        "--stdio"
      ],
      "env": {
        "DEBUG": "1"
      }
    }
  }
}

Replace:

• /Users/you/dev/yourpythoncodebase with the absolute path of your project.
• /opt/homebrew/bin/pyright with the path to your language server (find it using the which command, e.g., which pyright).
• Any arguments after the -- symbol will be passed as arguments to the language server.
• Replace --stdio with the arguments required by other backends.

In a development environment, refer to configuration for setup.

Debugging

Include

env: {
  "DEBUG": 1
}

to get detailed LSP and application logs. Provide as much information as possible when reporting issues.

Roadmap

• [x] Read definition
• [x] Find references
• [x] Apply edits
• [x] Get diagnostics
• [x] Code lenses
• [ ] Hover information
• [ ] Code actions
• [ ] Better context and cancellation handling
• [ ] Add language server configuration options
• [ ] Create a more consistent and extensible tool API (pagination, etc.)

📚 Documentation

This codebase uses modified code from gopls to handle LSP communication. See ATTRIBUTION for details.

[mcp - golang](https://github.com/metoro - io/mcp - golang) is used for MCP communication.