fyuuki0jp/vscode-debugger-mcp

VSCode Debugger MCP Server

VSCode extension that provides an MCP (Model Context Protocol) server for debugging integration.

Features

This extension provides MCP tools for controlling VSCode's debugger:

• Breakpoint Management: Set and remove breakpoints in your code
• Expression Evaluation: Evaluate expressions during debug sessions
• Debug Configuration: List available debug configurations from launch.json
• Session Control: Start and stop debugging sessions
• Step Execution: Control debugger stepping (step over, into, out, continue, pause)
• Status Monitoring: Get current debug status including active sessions and breakpoints

MCP Tools

set_breakpoint

Set a breakpoint at a specific line in a file. Supports both absolute and relative paths.

{
  "path": "src/index.js",  // relative to workspace
  "line": 42,
  "condition": "i > 10"  // optional
}

remove_breakpoint

Remove a breakpoint at a specific line. Supports both absolute and relative paths.

{
  "path": "src/index.js",  // relative to workspace
  "line": 42
}

evaluate_expression

Evaluate an expression in the current debug context.

{
  "expression": "myVariable.someProperty",
  "frameId": 0  // optional
}

list_debug_configurations

List all available debug configurations from launch.json files.

start_debugging

Start a debugging session.

{
  "configName": "Run Extension"  // optional
}

stop_debugging

Stop the current debugging session.

get_debug_status

Get the current debug status including:

• Active session information
• Available threads and active thread ID
• Stack frames (when paused)
• Breakpoints with relative paths

Example response:

{
  "isActive": true,
  "isPaused": true,
  "activeSession": {
    "id": "1",
    "name": "Launch Program",
    "type": "node"
  },
  "threads": [
    { "id": 1, "name": "main" }
  ],
  "activeThreadId": 1,
  "stackFrames": [
    {
      "id": 1,
      "name": "myFunction",
      "source": { "path": "src/index.js", "name": "index.js" },
      "line": 42,
      "column": 5
    }
  ],
  "breakpoints": [...]
}

step_debugger

Control debugger stepping during an active debug session.

{
  "type": "stepOver",  // stepOver, stepInto, stepOut, continue, pause
  "threadId": 1  // optional - defaults to active thread
}

Note: You can get the thread ID from get_debug_status. If not specified, the debugger will use the currently active thread.

Communication

The extension runs an SSE (Server-Sent Events) server on http://localhost:6010/sse for MCP client communication.

Endpoints

• GET /sse - SSE connection endpoint
• POST /sse - Send MCP requests
• GET /health - Health check endpoint

Development

1. Clone the repository
2. Run npm install
3. Open in VSCode
4. Press F5 to run the extension in a new Extension Development Host window

Building the Extension

Standard Build

npm run build

This creates vscode-debugger-mcp-0.0.1.vsix file.

Optimized Bundle Build

npm run package-bundle

This creates a webpack-bundled version for better performance.

Available Scripts

• npm run compile - Compile TypeScript to JavaScript
• npm run watch - Watch mode compilation
• npm run lint - Run ESLint
• npm run package - Create .vsix package
• npm run build - Compile and package
• npm run webpack - Bundle with webpack
• npm run package-bundle - Bundle and package

Installation

1. Build the extension using one of the methods above
2. In VSCode, go to Extensions view
3. Click the "..." menu and select "Install from VSIX..."
4. Select the generated .vsix file

Usage

1. The MCP server starts automatically when the extension activates
2. Connect your MCP client to http://localhost:6010/sse
3. Send JSON-RPC 2.0 requests to control the debugger

Commands

• Start MCP Debug Server - Manually start the server
• Stop MCP Debug Server - Stop the server
• Click the status bar item to toggle the server

Requirements

• VSCode 1.80.0 or higher
• Node.js 16.x or higher

License

MIT License - see file for details.