VSCode LSP MCP

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🔍 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!

⚙️ 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