---
name: debug
description: Start a debugging session for a file with real breakpoints and stepping
arguments:
- name: file
description: Path to the file to debug
required: true
- name: line
description: Optional line number for initial breakpoint
required: false
---
# Debug Session
The MCP debugger tools are ALREADY AVAILABLE. Do NOT search for .mcp.json or config files. Just call the tools directly.
I'll help you debug `$ARGUMENTS.file` using the MCP debugger.
## Instructions
1. **Detect Language**: First, determine the programming language from the file extension:
- `.py` → Python (uses debugpy)
- `.js`, `.ts`, `.mjs`, `.tsx` → JavaScript/TypeScript (uses vscode-js-debug)
- `.go` → Go (uses Delve)
- `.rs` → Rust (uses CodeLLDB)
2. **Create Session**: Use `create_debug_session` with the detected language
3. **Set Breakpoints**: If a line number was provided, use `set_breakpoint` to add an initial breakpoint. Otherwise, suggest strategic breakpoints based on the code.
4. **Start Debugging**: Use `start_debugging` with the script path
5. **When Stopped**: When the program pauses at a breakpoint:
- Use `get_source_context` to show the code around current location
- Use `get_variables` to display local variables
- Use `get_stack_trace` to show the call stack
- Explain what the code is doing at this point
6. **Interactive Debugging**:
- Ask if the user wants to step (in/over/out), continue, or inspect something
- Use `evaluate_expression` to test hypotheses about variable values
- Use `expand_variable` to drill into complex objects
7. **Cleanup**: When done, use `terminate_session` to clean up
## Tips
- Set breakpoints before where you expect the issue to occur
- Compare expected vs actual variable values
- Watch for null/undefined values or unexpected types
- Check loop counters and array indices
