python-debugger

A Claude Code plugin marketplace containing the Python Debugger plugin - PyCharm-like debugging for Python scripts.

Why Use This Skill?

The Problem

When Claude Code encounters a bug in Python code, it typically resorts to:

• •Adding print statements and re-running
• •Reading code and guessing what's wrong
• •Making changes based on assumptions without verifying them

This is inefficient. Real developers don't debug this way—they use debuggers.

The Solution

This skill gives Claude Code the same debugging capabilities that developers use in PyCharm or VS Code:

• •Set breakpoints at specific lines or on exceptions
• •Step through code line by line to see exactly what happens
• •Inspect variables at any point during execution
• •Navigate the call stack to understand how execution reached a certain point
• •Evaluate expressions in the current context to test hypotheses

Why This Matters

1. Faster bug resolution - Instead of guessing and re-running, Claude can pause execution exactly where needed and inspect state directly.

1. Systematic debugging - The skill includes debugging methodology that teaches Claude to debug like an experienced developer: form hypotheses, verify assumptions, binary search for bugs.

1. Better accuracy - By actually observing runtime values rather than inferring them from code, Claude makes fewer mistakes when diagnosing issues.

1. Complex bug handling - Some bugs only manifest at runtime with specific data. Print debugging can't easily catch issues like race conditions, state mutations, or deep call stack problems. A real debugger can.

Example Scenario

Without this skill:

User: "This function returns wrong values sometimes"
Claude: *reads code* "I think the issue might be X. Let me add some prints..."
*adds prints, runs, reads output, guesses again*

With this skill:

User: "This function returns wrong values sometimes"
Claude: *sets conditional breakpoint* "Let me pause when the output looks wrong"
*inspects actual variable values at that moment*
"Found it - the input was None here because..."

Installation

1. Add the marketplace

/plugin marketplace add alonw0/python-debugger-skill

2. Install the plugin

/plugin install python-debugger@python-debugger-marketplace

Available Plugins

python-debugger

PyCharm-like Python debugging with breakpoints, stepping, variable inspection, and stack navigation.

Features:

• •Line, conditional, and exception breakpoints
• •Step into, step over, continue, finish
• •Variable inspection (locals, globals, eval, deep inspect)
• •Call stack navigation
• •Built-in debugging methodology and best practices

Usage: Just ask Claude Code to debug your Python scripts:

"Debug my_script.py - it's returning wrong values"
"Set a breakpoint at line 25 and inspect the variables"
"Why is this function crashing?"
"Step through the loop and show me what's happening"

Repository Structure

python-debugger-skill/
├── .claude-plugin/
│   └── marketplace.json
├── plugins/
│   └── python-debugger/
│       ├── .claude-plugin/
│       │   └── plugin.json
│       └── skills/
│           └── python-debugging/
│               ├── SKILL.md
│               ├── scripts/
│               │   ├── debugger.py
│               │   └── inspector.py
│               └── references/
│                   ├── methodology.md
│                   ├── commands.md
│                   ├── examples.md
│                   └── troubleshooting.md
├── examples/
│   └── buggy_calculator.py      # Try debugging this!
└── README.md

Try It Out

The repo includes an example buggy script with 3 intentional bugs. After installing the plugin, ask Claude Code to debug it.

1. First, see the bugs in action

python examples/buggy_calculator.py

You'll see incorrect outputs and errors.

2. Ask Claude Code to debug

Once the plugin is installed, just ask Claude Code naturally:

"Debug examples/buggy_calculator.py - it's crashing on empty lists"

"Help me find why calculate_total_price returns wrong values on the second call"

"Step through process_user_data and figure out why it's missing users"

Claude Code will automatically use the python-debugging skill to:

• •Start a debug session
• •Set appropriate breakpoints
• •Step through the code
• •Inspect variables
• •Identify the root cause
• •Explain what's wrong and how to fix it

Example Debugging Session

You: "Debug examples/buggy_calculator.py - the calculate_total_price function returns wrong values"

Claude Code: Uses the debugging skill to:

1. Start the debugger on the script
2. Set a breakpoint inside apply_discount
3. Continue and inspect the discounts list
4. Notice it accumulates across calls (mutable default argument bug)
5. Explain the issue and suggest the fix

What Claude Code Can Debug

Just describe the problem naturally:

• •"This script crashes sometimes, help me find why"
• •"Why does this function return None?"
• •"Debug this - the loop skips some items"
• •"Set a breakpoint at line 45 and show me what's in the data variable"
• •"Step through the calculate function and explain what's happening"

Requirements

• •Python 3.7+
• •macOS or Linux

License

MIT