MCP Server for VS Code

A VS Code extension that provides a Model Context Protocol (MCP) server, enabling AI assistants to interact with your VS Code environment for language intelligence, debugging, and code execution.

Features

• Language Intelligence: Access VS Code's language server features including:

  • Go to definition
  • Find references
  • Diagnostics (errors and warnings)
  • Symbol search
  • Call hierarchy

• Debugging Support: Control VS Code's debugger programmatically:

  • Start/stop debug sessions
  • Set and manage breakpoints
  • Step through code (into/over/out)
  • Inspect variables and call stacks
  • Evaluate expressions in debug context

Installation

Alpha Testing

Step 1: Install VS Code Extension

Download the .vsix file from Releases and install:

• In VS Code: Extensions → ... menu → Install from VSIX
• Or via command line: code --install-extension mcp-server-vscode-*.vsix

Step 2: Configure Claude Desktop

The MCP server runs directly from GitHub using npx. Add this to your Claude config:

• macOS: ~/Library/Application Support/Claude/claude_desktop_config.json
• Windows: %APPDATA%\Claude\claude_desktop_config.json

{
  "mcpServers": {
    "vscode": {
      "command": "npx",
      "args": ["github:malvex/mcp-server-vscode"]
    }
  }
}

Step 3: Restart Claude Desktop

That's it! The VS Code tools are now available in Claude.

Configure Claude Code (CLI)

For Claude Code users, run this one-liner:

claude mcp add-json vscode '{"type":"stdio","command":"npx","args":["github:malvex/mcp-server-vscode"]}' -s user

Usage

Once installed, the extension shows the MCP server status in the VS Code status bar (bottom right).

To start the MCP server: Click on "VS Code MCP: Stopped" in the status bar. It will change to "VS Code MCP: 8991" when running.

The status bar indicates:

• VS Code MCP: 8991 - Server is running on port 8991
• VS Code MCP: Stopped - Server is not running

Click the status bar item to toggle the server on/off.

How It Works

┌─────────────┐     stdio      ┌──────────────────┐     HTTP      ┌─────────────┐
│   Claude    │ ◄────────────► │  MCP Standalone  │ ◄───────────► │   VS Code   │
│   Desktop   │                │      Server      │    :8991      │  Extension  │
└─────────────┘                └──────────────────┘               └─────────────┘

1. VS Code Extension provides an HTTP API on port 8991
2. MCP Standalone Server acts as a bridge, converting stdio ↔ HTTP
3. Claude Desktop communicates with the standalone server via stdio

Troubleshooting

If Claude can't connect to VS Code:

1. Check VS Code is running with the extension active
2. Check the status bar shows "VS Code MCP: 8991"
3. Test the MCP server: Run npx github:malvex/mcp-server-vscode in terminal
4. Check firewall isn't blocking localhost:8991
5. Try manually starting the MCP server in VS Code (Cmd/Ctrl+Shift+P → "Start MCP Server")

Available Tools

The extension provides 25 tools organized into three main categories:

Language Intelligence Tools (7 tools)

Refactoring Tools (1 tool)

Debug Tools (17 tools)

Breakpoint Management

Session Management

Runtime Control

Inspection and Evaluation

Tool Features

All tools support:

• Compact format - Optimized for AI token efficiency
• Detailed format - Full data for complex analysis
• Symbol-based navigation - Work with names instead of file/line numbers
• Workspace-wide operations - Not limited to single files
• Language server integration - Accurate semantic understanding

Usage Examples for AI Assistants

When connected via MCP, AI assistants can use these tools to help users with development tasks:

Finding and Understanding Code

User: "What does the handleRequest function do?"
AI uses: hover({ symbol: "handleRequest" })
→ Gets type signature and documentation without reading entire files

User: "Where is the DatabaseConnection class defined?"
AI uses: definition({ symbol: "DatabaseConnection" })
→ Instantly finds the file and line where it's declared

User: "Show me all places where processPayment is called"
AI uses: callHierarchy({ symbol: "processPayment", direction: "incoming" })
→ Gets complete list of callers with their locations

Refactoring

User: "Rename the oldMethodName method to newMethodName everywhere"
AI uses: refactor_rename({ symbol: "oldMethodName", newName: "newMethodName" })
→ Safely renames across all files, updating imports and references

Debugging

User: "Help me debug why the server crashes"
AI uses: debug_listConfigurations({})
→ Shows available debug configurations

AI uses: debug_startSession({ configuration: "Debug Server" })
→ Starts the debug session

User: "Set a breakpoint where errors are handled"
AI uses: debug_setBreakpoint({ symbol: "handleError" })
→ Sets breakpoint on the function

User: "What's the value of the user object here?"
AI uses: debug_inspectVariables({ scope: "locals", filter: "user" })
→ Shows current value of user variable in debug context

User: "Why is this condition true?"
AI uses: debug_evaluateExpression({ expression: "users.length > 0 && isActive" })
→ Evaluates the expression in current debug scope

Development

Building from Source

# Clone the repository
git clone https://github.com/malvex/mcp-server-vscode.git
cd mcp-server-vscode

# Install dependencies
npm install

# Build everything
npm run compile
npm run package

# Package the VS Code extension
npx vsce package

Testing Local Changes

To test your local development version:

1. VS Code Extension: Press F5 in VS Code to launch Extension Development Host
2. MCP Server: Update Claude config to use local path:

{
  "mcpServers": {
    "vscode": {
      "command": "node",
      "args": ["/path/to/mcp-server-vscode/out/mcp/standalone-server.js"]
    }
  }
}

License

This project is licensed under the MIT License - see the LICENSE file for details.