# mcp-debugger (MCP server)

> mcp-debugger is an MCP server that adds developer tools to AI assistants such as Claude Desktop, Claude Code and Cursor. Step-through debugging for AI agents: breakpoints, stepping and live variables in nine languages. It has 171 GitHub stars, is released under the MIT license and runs locally with npx -y @debugmcp/mcp-debugger.

A headless, agentic debugger over MCP — let your AI agents debug running programs in nine languages. mcp-debugger is a Model Context Protocol (MCP) server that exposes step-through debugging as structured tool calls. It lets AI agents set breakpoints, inspect variables, evaluate expressions, and step through running programs across nine languages — driving real language debuggers through the Debug Adapter Protocol (DAP).

## Key facts

| Fact | Value |
|---|---|
| Repository | https://github.com/debugmcp/mcp-debugger |
| GitHub stars | 171 |
| License | MIT |
| Language | TypeScript |
| Transport | stdio |
| Packages | npm: @debugmcp/mcp-debugger; docker: docker.io/debugmcp/mcp-debugger:0.25.1 |
| Remote URL | none |
| Needs API key | no |
| Official | yes |
| Works with | Claude Desktop, Claude Code, Cursor, VS Code |
| Category | Developer tools |
| Latest release | v0.25.1 (Sep 30, 2026) |
| Last commit | Oct 6, 2026 |
| MCP registry name | io.github.debugmcp/mcp-debugger |

## Install

### Claude Desktop (claude_desktop_config.json)

```json
{
  "mcpServers": {
    "mcp-debugger": {
      "command": "npx",
      "args": [
        "-y",
        "@debugmcp/mcp-debugger"
      ]
    }
  }
}
```

Settings > Developer > Edit Config. macOS: ~/Library/Application Support/Claude/, Windows: %APPDATA%\Claude\. Restart Claude Desktop afterwards.

### Claude Code

```sh
claude mcp add --transport stdio mcp-debugger -- npx -y @debugmcp/mcp-debugger
```

### Cursor (.cursor/mcp.json)

```json
{
  "mcpServers": {
    "mcp-debugger": {
      "type": "stdio",
      "command": "npx",
      "args": [
        "-y",
        "@debugmcp/mcp-debugger"
      ]
    }
  }
}
```

Project file; use ~/.cursor/mcp.json to enable it in every project.

### VS Code (.vscode/mcp.json)

```json
{
  "servers": {
    "mcp-debugger": {
      "type": "stdio",
      "command": "npx",
      "args": [
        "-y",
        "@debugmcp/mcp-debugger"
      ]
    }
  }
}
```

Config formats checked against the official docs on 2026-10-07.

## Tools

- `create_debug_session`: Create a new debugging session
- `list_debug_sessions`: List all active sessions
- `list_supported_languages`: Show available language adapters
- `set_breakpoint`: Set a breakpoint in a file
- `list_breakpoints`: List a session's breakpoints with verified state
- `remove_breakpoint`: Remove a breakpoint by id or file+line
- `clear_breakpoints`: Remove all breakpoints (optionally per file)
- `start_debugging`: Start debugging a script
- `restart_debugging`: Relaunch with the same config, breakpoints re-applied
- `attach_to_process`: Attach debugger to a running process
- `detach_from_process`: Detach debugger from a process
- `expose_session`: Open a read-only DAP mirror endpoint so an IDE can attach and inspect
- `unexpose_session`: Close the mirror endpoint and disconnect IDE clients
- `get_stack_trace`: Get the current stack trace
- `list_threads`: List all threads in the debug session
- `get_scopes`: Get variable scopes for a frame
- `get_variables`: Get variables in a scope
- `get_local_variables`: Get local variables in current frame
- `step_over`: Step over the current line
- `step_into`: Step into a function
- `step_out`: Step out of a function
- `continue_execution`: Continue running
- `wait_for_stop`: Block until the session next pauses or ends
- `pause_execution`: Pause running execution
- `evaluate_expression`: Evaluate expressions in debug context
- `get_source_context`: Get source code context
- `get_output`: Read captured debuggee output (stdout/stderr)
- `close_debug_session`: Close a session
- `redefine_classes`: Hot-swap changed Java classes into a running JVM (Java only)

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