LSP MCP Bridge

A Visual Studio Code extension that exposes any Language Server Protocol (LSP) capabilities as Model Context Protocol (MCP) tools and GitHub Copilot Language Model Tools. This universal extension works with any programming language that has an active language server in VSCode.

I created this because I work on an incredibly large C++ project (with clangd) and Copilot is not able find objects efficiently.

✨ Demo

Here's a quick example of how the extension enhances GitHub Copilot's understanding of a C++ codebase.

1. A sample C++ project:

A small excerpt of the C++ project used in the demo.

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2. Copilot's enhanced answer: Copilot's response enriched with precise definitions, references, and hover info provided by the LSP-MCP bridge.

3. Asking Copilot about the code: Copilot queries the registered LSP tools (workspace/document symbols, references) to find the symbol and its implementation.

🎯 Purpose

This extension bridges the gap between any existing language server's capabilities and MCP clients + GitHub Copilot, enabling AI models and tools to:

• Navigate codebases intelligently across any programming language
• Provide context-aware code suggestions and analysis
• Answer questions about code structure and functionality
• Assist with code refactoring and analysis
• Automatically enhance GitHub Copilot with deep language server insights

🚀 Features

Language Model Tools for GitHub Copilot (10 Tools)

The extension exposes comprehensive LSP capabilities as GitHub Copilot tools that can be used automatically:

1. lsp_definition - Find symbol definitions
2. lsp_references - Find all references to a symbol
3. lsp_hover - Get symbol information and documentation
4. lsp_completion - Get code completion suggestions
5. lsp_workspace_symbols - Search symbols across the workspace
6. lsp_document_symbols - Get document structure/outline
7. lsp_rename_symbol - Preview symbol rename impact
8. lsp_code_actions - Get available quick fixes and refactorings
9. lsp_format_document - Preview document formatting
10. lsp_signature_help - Get function signature and parameter help

Universal Language Support

Works with any programming language that has an active language server in VSCode:

• Python (Pylance, Jedi)
• TypeScript/JavaScript (Built-in)
• Rust (rust-analyzer)
• Go (Go extension)
• C/C++ (C/C++ extension, clangd)
• Java (Language Support for Java)
• C# (.NET extension)
• PHP (Intelephense)
• Ruby (Solargraph)
• And many more...

📦 Installation

🎯 Recommended: From VS Code Marketplace

Method 1: Direct Link

1. Click here: Install LSP MCP Bridge
2. Click "Install" on the marketplace page
3. VS Code will open and install the extension automatically

Method 2: In VS Code

1. Open VS Code
2. Press Ctrl+Shift+X (or Cmd+Shift+X on Mac) to open Extensions
3. Search for "LSP MCP Bridge" or "sehejjain.lsp-mcp-bridge"
4. Click "Install"

Method 3: Command Line

code --install-extension sehejjain.lsp-mcp-bridge

Prerequisites

• Visual Studio Code 1.75.0 or later
• Any language server configured in your VSCode environment (automatically works with existing setups)

Alternative: From VSIX Package

For development or testing purposes:

1. Download the latest lsp-mcp-bridge-0.0.1.vsix release
2. Install the extension:

   code --install-extension lsp-mcp-bridge-0.0.1.vsix
   

3. Reload VSCode
4. The tools are automatically available to GitHub Copilot!

From Source

1. Clone this repository:

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

2. Install dependencies:

   npm install
   

3. Compile and package:

   npm run compile
   npx @vscode/vsce package
   

4. Install the extension:

   code --install-extension lsp-mcp-bridge-0.0.1.vsix
   

🛠️ Usage

With GitHub Copilot (Automatic)

Once installed, all LSP tools are automatically available to GitHub Copilot. Copilot will use them automatically when:

• You ask about code structure or symbols
• You need to understand unfamiliar code
• You want to find references or definitions
• You're working on refactoring tasks
• You ask for code suggestions or improvements

Example: Just ask Copilot "What does this function do?" while your cursor is on a function, and it will automatically use the hover and definition tools to provide a comprehensive answer.

Auto-Discovery by VS Code

The extension automatically registers itself with VS Code's MCP system, so:

• No manual startup required - Tools are immediately available
• Automatic tool discovery - VS Code finds the extension's capabilities automatically
• Seamless integration - Works with VS Code's built-in MCP support

Manual Testing

Use the Command Palette (Ctrl+Shift+P / Cmd+Shift+P):

1. "LSP MCP: Test MCP Tools at Cursor" - Test the core tools at your cursor position
2. "LSP MCP: List Language Model Tools" - See all 10 registered tools

With External MCP Clients

The extension also automatically registers with VS Code's MCP system, making it discoverable by external MCP clients without any additional configuration.

🔧 Configuration

No additional configuration required! The extension automatically works with any language servers you have configured in VSCode.

Supported Language Servers

The extension works with any LSP-compliant language server installed in VSCode:

🧪 Testing

Run the comprehensive test suite:

npm test

The test suite includes:

• Unit tests for all LSP client methods
• Mock implementations for testing
• Integration tests for MCP server functionality
• Type validation tests
• GitHub Copilot tool registration tests

📚 API Reference

Language Model Tools

All tools are automatically registered with GitHub Copilot and can be referenced by their toolReferenceName:

Input Schemas

All tools use consistent input schemas based on LSP specifications:

Position-based tools (definition, references, hover, completion, signature_help):

{
  uri: string;        // File URI (e.g., "file:///path/to/file.py")
  line: number;       // 0-based line number
  character: number;  // 0-based character offset
}

Workspace symbol search:

{
  query: string;      // Search query for symbol names
}

Document symbols:

{
  uri: string;        // File URI
}

Code actions:

{
  uri: string;
  range: {
    start: { line: number; character: number };
    end: { line: number; character: number };
  };
}

🔍 How It Works

1. Extension Activation: Registers all 10 LSP tools with VSCode's Language Model API
2. GitHub Copilot Integration: Tools are automatically available to Copilot via toolReferenceName
3. LSP Bridge: Uses VSCode's executeCommand API to access any active language server
4. Universal Support: Works with any LSP-compliant language server
5. No Extra Processes: Reuses existing language server connections

🐛 Troubleshooting

Tools Not Appearing in Copilot

• Ensure VSCode is version 1.103.0 or later
• Reload VSCode after installation
• Check that the extension is enabled in Extensions view

No Results from Tools

• Ensure you have a language server active for your file type
• Check that the file is saved and language server is initialized
• Verify cursor position is on a valid symbol

Language Server Not Working

• Install the appropriate language extension for your programming language
• Check VSCode's Output panel for language server logs
• Ensure your project is properly configured (e.g., package.json for Node.js)

🤝 Contributing

1. Fork the repository
2. Create a feature branch: git checkout -b feature/new-capability
3. Make your changes and add tests
4. Run the test suite: npm test
5. Submit a pull request

📄 License

MIT License - see LICENSE file for details.

🙏 Acknowledgments

• Built on top of VSCode's excellent Language Server Protocol support
• Inspired by the Model Context Protocol specification
• Designed to enhance GitHub Copilot's capabilities