LSP MCP Server

An LSP (Language Server Protocol) MCP (Model Context Protocol) server that provides refactoring tools through LSP integration. This server exposes refactoring capabilities as MCP tools that can be used by MCP clients like Claude Code.

Installation

From npm (when published)

npm install -g lsp-mcp-server

Local Development Setup

1. Clone the repository:

   git clone <repository-url>
   cd lsp-mcp-server
   

2. Install dependencies:

   pnpm install
   

3. Build the project:

   pnpm run build
   

4. Link for global use:

   npm link
   

   After linking, you can use the mcp-lsp command globally.

5. Alternative: Use without linking:

   # Run directly
   pnpm start
   
   # Or build and run
   pnpm run dev
   

Prerequisites

The server requires these language servers to be installed for full functionality:

TypeScript/JavaScript

npm install -g typescript-language-server typescript

Python

# Default LSP server for type checking and refactoring
npm install -g pyright

# Optional: For linting (when using serverType: 'lint')
pip install ruff

Usage

With Claude Code

Quick Setup (Recommended)

If you have the server installed globally:

/mcp add lsp-mcp

Using the Tools in Claude Code

Once connected, you can ask Claude Code to use the refactoring tools:

• "Rename the calculateTotal function to computeSum in src/utils.ts on line 45"
• "Find all references to the UserService class in src/services/user.ts line 12"
• "Extract lines 20-35 from src/components/Header.tsx into a new function called renderNavigation"
• "Move the validateEmail function from src/utils/validation.ts line 8 to src/utils/email.ts"
• "Rename the file src/old-name.ts to src/new-name.ts"

Claude Code will automatically use the appropriate LSP refactoring tools based on your requests.

Manual MCP Server Usage

The server can also be used directly by other MCP clients via stdio:

mcp-lsp

Available Tools

1. rename_file - Rename files/folders using LSP rename capabilities
2. move_function - Move functions between files using LSP refactoring
3. extract_function - Extract code selections into new functions
4. find_references - Find all references to symbols
5. rename_symbol - Rename symbols across all files

Example Tool Usage

Each tool accepts parameters specific to the refactoring operation:

• rename_symbol: Requires file, line, newName, and optionally character and language
• find_references: Requires file, line, and optionally character and language
• extract_function: Requires file, startLine, endLine, functionName, and optionally character positions and language

Supported Languages

• TypeScript/JavaScript
• Python

Development

Commands

• pnpm install - Install dependencies
• pnpm run build - Compile TypeScript to dist/
• pnpm start - Run the compiled server
• pnpm run dev - Build and run in one command
• pnpm run type-check - Check types without building
• pnpm run lint - Check code with ESLint
• pnpm run lint:fix - Auto-fix linting issues
• pnpm run format - Format code with Prettier
• pnpm run clean - Remove dist/ directory

Architecture

The server consists of:

• LSPRefactorServer: Main server class implementing MCP interface
• LSP Client Management: Manages connections to language servers
• Tool Implementations: Each refactoring operation communicates with LSP servers

Protocol Communication

• MCP Protocol: Server ↔ MCP clients via stdio
• LSP Protocol: Server ↔ Language servers via JSON-RPC over stdio