Claude Debugs For You MCP

Install

Works in

• Claude Desktop
• Cursor
• VS Code
• SourceCraft
• Koda
• Coddy

Manual install

{
  "mcpServers": {
    "debug": {
      "command": "node",
      "args": [
        "/path/to/mcp-debug.js"
      ]
    }
  }
}

What it does

The extension starts an MCP HTTP server inside VS Code on port 4711, and an agent connects to it. For clients that only speak stdio (Claude Desktop), the extension adds a small `mcp-debug.js` script that forwards calls to the extension's server. Clients with SSE support (Cursor) need only the address `http://localhost:4711/sse`. The agent gets three tools. `listFiles` lists workspace files by include and exclude patterns, and `getFileContent` returns a file with line numbers by absolute path. The third, `debug`, takes a plan of steps: `setBreakpoint` (with an optional condition), `removeBreakpoint`, `launch`, `continue` and `evaluate`. Launch takes the first configuration from `.vscode/launch.json` and substitutes the current file for `${file}`. After each step the agent gets the debugger's reply: the stop location, values of evaluated expressions and errors, and since version 0.1.2 exceptions as well. It works with anything that has a debug adapter and a debugger console in VS Code, including Python and C++.

Who it is for. For VS Code developers whose code misbehaves and who want an agent to step through it in the debugger instead of guessing from the text.

Example request

The function longest_substring_with_k_distinct returns the wrong thing. Walk through it in the debugger step by step with breakpoints and find where the values diverge from what is expected

MCP

Transport

stdio, sse

Authentication

not required

Limitations

The project is at version 0.1.2, and the repository's last change dates from December 20, 2025. MIT License. VS Code 1.96 or newer is required.

The agent works with code and values in the process the debugger started. Expressions in `evaluate` run in the context of the debugged program, so debug only projects you trust.

The extension listens on port 4711 (the `mcpDebug.port` setting) and creates a server with no explicit binding to `localhost`. If the port is reachable from the network, anyone who gets network access to it can call its tools, and the server has no access check.

The server starts together with VS Code (`mcpDebug.autostart` is on by default), and only one runs across several windows: the extension offers to hand it off to another window. Launch uses only the first configuration from `launch.json`.

Step order matters: set breakpoints before launching or while paused, and do not use `continue` to reach the first breakpoint.

How to disable. Turn off autostart with the `mcpDebug.autostart` setting or stop the server with the Claude Debugs For You: Stop Server command. To remove it fully, uninstall the extension from VS Code and delete the `debug` block from `claude_desktop_config.json` or the address from the client settings.

README in short

The repository shows how to install the extension and connect a client over stdio or SSE, and gives a sample prompt for the agent. It has video demos with Continue and Claude Desktop, a Continue setup with an experimental servers block and notes on building the extension and the package with `vsce package`. Sources are in `src` (the extension and server) and `mcp` (the stdio script), Python examples in `examples`, and the version history in `CHANGELOG.md`.