mcp-debugger
A debugger with no IDE: an agent sets breakpoints, steps through code and inspects variables in ten languages
- 188 ★ on the repository
- Last commit
- MIT
Broad access
Why this level
- Debugging runs your program with the agent rights and evaluated expressions execute code inside it
- Attaching to processes on other machines and pods exposes their state and data
Install
- Works in
Manual install
npx -y @debugmcp/mcp-debugger stdioRuns over stdio; clients start it themselves.
Access and checks
How we reviewBroad accessThe tool can change data, run commands or handle secrets.
- Debugging runs your program with the agent rights and evaluated expressions execute code inside it
- Attaching to processes on other machines and pods exposes their state and data
This is third-party code. Review the repository files before installing.
What it does
mcp-debugger turns step-through debugging into MCP calls. The agent runs a program under the real language debugger through the Debug Adapter Protocol, sets breakpoints, steps, evaluates expressions and inspects the stack and variables. Supported are Python (debugpy), JavaScript and Node.js (js-debug), Ruby (rdbg), Rust and C/C++ (CodeLLDB), Go (Delve), Java (JDI), .NET (netcoredbg), COBOL and Dart with Flutter, including hot reload. No IDE is needed: the server works anywhere Node.js runs, that is CI, containers, Kubernetes pods, SSH boxes and cloud agent sandboxes. It can attach to a process on another machine without an IDE and has logpoints that log without pausing the program. Transport is stdio or Streamable HTTP and every debug session gets its own process. By default variable, expression and output values are masked for secrets. The repository installs as an npm package, a Docker image and a skill.
Who it is for. Developers whose agent works in a terminal, CI or cloud sandbox and must find bugs with a debugger and not by adding prints.
Good fit when
- A test fails only in a container and the agent attaches a debugger to a process in a Kubernetes pod
- An exception is rare and the agent sets a conditional breakpoint and inspects local variables
- A Flutter app behaves oddly and the agent changes code with hot reload
- Production cannot be paused so logpoints record values to a log
- Legacy COBOL is stepped through and WORKING-STORAGE values are inspected
Not a fit when
- The agent works inside an open VS Code: a server that drives the editor debugger fits better
- You need a PHP debugger: that language is not in the list
- The bug is visible from a log and trace: launching a debugger is overkill
Example request
Run `app.py` under the debugger, set a breakpoint in the `parse_order` function and show variable values at the failureMCP
- Transport
- stdio, http
- Authentication
- not required
Limitations
The server launches the language debugger, which must be available on the machine: Java needs JDK 21 or newer, Rust on Windows needs the GNU toolchain and C/C++ goes through CodeLLDB. Debugging runs your program with the agent rights and `evaluate` expressions execute code inside it. Secret masking is on by default but make sure parameters do not turn it off. PHP is not supported. Some features, such as Java hot swap and Flutter reload, depend on the language adapter.
How to disable. Remove the server in the client (`claude mcp remove mcp-debugger`) and stop any running debug sessions.
FAQ
How do I connect mcp-debugger?
Add the command `npx -y @debugmcp/mcp-debugger stdio` to the client MCP config. For Codex: `codex mcp add mcp-debugger -- npx -y @debugmcp/mcp-debugger stdio`.
Which languages are supported?
Python, JavaScript and TypeScript, Ruby, Rust, Go, Java, .NET, C and C++, COBOL, Dart and Flutter.
Is VS Code required?
No, the server runs as a standalone Node.js process. An `expose_session` mode shows the agent session in an IDE as read-only.
Can I debug a process in Kubernetes?
Yes. Pods connect through port-forward for debugpy, rdbg and JDWP, and native code has a `kubectl debug` flow with an ephemeral container.
Do secrets leak into agent answers?
By default variable, expression and output values are masked and a least-privilege mode restricts access further. Check the settings before running on live data.
Discussion
No questions or reviews yet.
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README in short
The README compares the server with a VS Code based debugger in a feature table, lists supported languages and leads to installation through npx, Docker and a skill. Separate sections cover Kubernetes, Dart and Flutter, logpoints and secret masking.