VSCode LSP MCP

🔍 Overview

VSCode LSP MCP is a Visual Studio Code extension that exposes Language Server Protocol (LSP) features through the Model Context Protocol (MCP).

Extension ID: cjl.lsp-mcp — open Extensions (Ctrl+Shift+X / Cmd+Shift+X) and search for cjl.lsp-mcp to find this plugin precisely.

This allows AI assistants and external tools to utilize VSCode's powerful language intelligence capabilities without direct integration.

🌟 Why This Extension?

Large language models like Claude and Cursor struggle to understand your codebase accurately because:

• They rely on regex patterns to find symbols, leading to false matches

• They can't analyze import/export relationships properly

• They don't understand type hierarchies or inheritance

• They have limited code navigation capabilities

This extension bridges that gap, providing AI tools with the same code intelligence that VSCode uses internally!

Related MCP server: MCP Server

⚙️ Features

• 🔄 LSP Bridge: Converts LSP features into MCP tools

• 🔌 Multi-Instance Support: Automatically handles port conflicts for multiple VSCode windows

• 🧠 16 LSP operations covering navigation (definition, declaration, implementation, references), documentation (hover, completions), structure (document/workspace symbols, call hierarchy), and manipulation (rename)

• ☕ Java dependency source: Get decompiled Java class source via jdt:// URI (from jdtls), so AI can read library implementations

• 📄 Dual output format: JSON for machine processing, Markdown for LLM-friendly reading

🛠️ Exposed MCP Tools

All operations are invoked through the single execute_lsp MCP tool with a unified input format:

• operation — which LSP operation to execute

• uri — file path or URI string (supports both plain paths and file:///jdt:// URIs)

• line — line number (1-based, matching editor display). Required for position-dependent operations

• character — character offset (1-based, matching editor display). Required for position-dependent operations

• newName — required only for rename

• query — required only for workspace_symbols

1-based positions: Both input and output use 1-based line/character values, matching what your editor displays. VS Code shows Ln 9, Col 16 → pass line: 9, character: 16. Output positions can be used directly as input for the next call — no conversion needed.

📋 Configuration

🔗 Integration with AI Tools

Cursor

Config file: ~/.cursor/mcp.json (e.g. %USERPROFILE%\.cursor\mcp.json on Windows)

{
  "mcpServers": {
    "lsp": {
      "url": "http://127.0.0.1:9527/mcp"
    }
  }
}

OpenCode

Config file: ~/.config/opencode/opencode.jsonc

{
  "mcp": {
    "lsp-mcp": {
      "type": "remote",
      "url": "http://127.0.0.1:9527/mcp",
      "enabled": true
    }
  }
}

Claude Code

Config file: ~/.claude.json

{
  "mcpServers": {
    "lsp-mcp": {
      "type": "http",
      "url": "http://127.0.0.1:9527/mcp"
    }
  }
}

Gemini | IFlow

Config file: ~/.gemini/settings.json

{
  "mcpServers": {
    "lsp-mcp": {
      "type": "streamable-http",
      "httpUrl": "http://127.0.0.1:9527/mcp"
    }
  }
}

Codex

Config file: ~/.codex/config.toml

[mcp_servers.lsp-mcp]
url = "http://127.0.0.1:9527/mcp"

Roo Code

{
  "mcpServers": {
    "lsp": {
      "type": "streamable-http",
      "url": "http://127.0.0.1:9527/mcp",
      "disabled": false
    }
  }
}

💻 Development

• Clone the repository

• Run pnpm install

• Run pnpm run update to generate metadata

• Press F5 to start debugging