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

vscode-ext demo

🌟 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!

⚙️ Features

🔄 LSP Bridge: Converts LSP features into MCP tools
🔌 Multi-Instance Support: Automatically handles port conflicts for multiple VSCode windows
🧠 Rich Code Context: Provides accurate symbol information through LSP
☕ Java dependency source: Get decompiled Java class source via jdt:// URI (from jdtls), so AI can read library implementations

🛠️ Exposed MCP Tools

Tool	Description
`get_hover`	Get hover information for symbols
`get_definition`	Find symbol definitions
`get_completions`	Get intelligent code completions
`get_references`	Find all references to a symbol
`get_class_file_contents`	Get decompiled Java class source via jdt:// URI (e.g. from `get_definition` when the target is in a dependency JAR)
`rename_symbol`	Rename symbols across files

📋 Configuration

Key	Description	Type	Default
`lsp-mcp.enabled`	Enable or disable the LSP MCP server.	`boolean`	`true`
`lsp-mcp.port`	Port for the LSP MCP server.	`number`	`9527`
`lsp-mcp.maxRetries`	Maximum number of port retry attempts when the default port is occupied.	`number`	`10`
`lsp-mcp.cors.enabled`	Enable or disable CORS (Cross-Origin Resource Sharing).	`boolean`	`true`
`lsp-mcp.cors.allowOrigins`	Allowed origins for CORS. Use `*` to allow all origins, or provide a comma-separated list of origins (e.g., `http://localhost:3000,http://localhost:5173`).	`string`	`*`
`lsp-mcp.cors.withCredentials`	Whether to allow credentials (cookies, authorization headers) in CORS requests.	`boolean`	`false`
`lsp-mcp.cors.exposeHeaders`	Headers that browsers are allowed to access. Provide a comma-separated list of headers (e.g., `Mcp-Session-Id`).	`string`	`Mcp-Session-Id`

🔗 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"
    }
  }
}

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

LSP MCP

CJL