Skills Guide

Debugger

VerifiedSafe

Use when the user provides an error, exception, stack trace, failing test, or “it doesn’t work”. Diagnose the root cause and propose minimal fixes with verification steps. Helps quickly identify the most likely cause and apply the smallest safe patch.

Download and use
Sby Skills Guide Bot
DevelopmentIntermediate
6/2/2026
Claude CodeCursorWindsurf
#error-diagnosis#debugging#stack-trace#fix-recommendation

Recommended for

Backend developerClaude CodeCode reviewFrontend developerCursorFullstack developer

Automated summary

Diagnoses the root cause of an error, exception, or failing test and proposes a minimal fix with verification steps.

Strengths

  • Structured analysis with multiple ranked hypotheses
  • Suggests minimal, safe patches
  • Includes a verification command to confirm the fix

Limitations

  • Requires a well-specified error (type, file, line)
  • May miss causes not visible in the call stack
  • Does not replace deep code understanding
When to use it

Use this skill whenever an error, exception, or test fails to get a quick diagnosis and targeted fix.

When not to use it

Do not use for architectural design issues or bugs requiring major refactoring without prior diagnosis.

Security analysis

Safe
Quality score80/100

The skill is a diagnostic advisory with no execution capabilities; it explicitly avoids suggesting destructive actions and contains no malicious content.

No concerns found

How this analysis is made

Examples

Fix TypeError in Python
I'm getting a TypeError: 'NoneType' object is not callable in my Python script at line 42. Here's the stack trace:
Traceback (most recent call last):
  File "app.py", line 42, in <module>
    result = my_function(arg)
  File "utils.py", line 15, in my_function
    return callback(value)
TypeError: 'NoneType' object is not callable
Debug failing Jest test
My Jest test is failing with the error: expect(received).toBe(expected) - Expected "success", received undefined. The test is in user.test.js, line 22. The test calls createUser() and expects the response to have a status property.

name: debugger description: Use when the user provides an error, exception, stack trace, failing test, or “it doesn’t work”. Diagnose and propose minimal fixes with verification steps.

Debugger Skill

Goal

Diagnose the root cause and propose the smallest safe fix.

Instructions

  1. Parse the error:
    • error type/message
    • file + line
    • call chain
  2. Generate 2–4 hypotheses ranked by likelihood.
  3. Inspect relevant files/logs if tools are available.
  4. Propose a minimal patch:
    • what to change
    • why it fixes root cause
  5. Provide verification:
    • command to run (tests/build)
    • expected outcome

Constraints

  • Prefer minimal diff.
  • Do not suggest destructive actions (delete/reset) unless clearly necessary and explicitly warned.

Output format

  • Diagnosis
  • Likely root cause
  • Minimal fix (patch/diff or steps)
  • How to verify

From the file to a first result

The download contains exactly the content displayed on this page. This copy may differ from the latest version in the source repository.

View the source and supporting files

This download contains SKILL.md only. Any scripts, references, templates and dependencies are not included. Get the required files from the source, preserving their directory structure, before continuing.

1. Download the file

Download SKILL.md

From the root of a test project, save the file as .skill-downloads/debugger-mm78noi3/SKILL.md, or use the command below. This folder is for inspecting the skill before installation.

Command for macOS/Linux or WSL: requires a POSIX shell and curl. On Windows without WSL, use the download button and create the folder manually.

mkdir -p '.skill-downloads/debugger-mm78noi3' && curl --fail --show-error --location 'https://skills-guides.com/api/skills/debugger-mm78noi3/download' --output '.skill-downloads/debugger-mm78noi3/SKILL.md.part' && mv '.skill-downloads/debugger-mm78noi3/SKILL.md.part' '.skill-downloads/debugger-mm78noi3/SKILL.md'

2. Check prerequisites

Read SKILL.md before using it. If it references scripts or external services, inspect them and prepare the required access in your test environment.

No recognized prerequisites section in this file. This does not mean it is self-contained: libraries, tools and access requirements may be mentioned elsewhere in the content or source repository.

The platforms on this page are catalog indications. The paths below follow tool documentation; they do not prove this skill has been run in those tools. No minimum tool version is confirmed for this listing.

3. Load the skill

After inspection, copy the complete folder into your project using one of the commands below, then open a new tool session. The command stops if a folder with the same name already exists: compare the files before replacing it.

Claude Code
test -f '.skill-downloads/debugger-mm78noi3/SKILL.md' && test -s '.skill-downloads/debugger-mm78noi3/SKILL.md' && mkdir -p '.claude/skills' && test ! -e '.claude/skills/debugger' && cp -R '.skill-downloads/debugger-mm78noi3' '.claude/skills/debugger'

Cursor
test -f '.skill-downloads/debugger-mm78noi3/SKILL.md' && test -s '.skill-downloads/debugger-mm78noi3/SKILL.md' && mkdir -p '.cursor/skills' && test ! -e '.cursor/skills/debugger' && cp -R '.skill-downloads/debugger-mm78noi3' '.cursor/skills/debugger'

OpenSkills

OpenSkills must already be installed. The local install/read procedure is checked with OpenSkills 1.5.0, which requires Node.js ≥ 20.6.0. Catalog slugs are not resolved automatically.

Official OpenSkills installation
openskills install './.skill-downloads/debugger-mm78noi3'

openskills read 'debugger-mm78noi3'

Reading should display the installed file content and its base directory. It does not run the skill or install its dependencies.

For an agent that reads AGENTS.md, then sync the index. This command changes AGENTS.md: review the diff before using it.

openskills sync

Manual method or another tool: attach SKILL.md to a conversation, or open it in an agent that can read files. Include any required supporting resources. No universal folder is recognized by every tool.

4. Try a first task

Use a short, synthetic input: an API endpoint, a small document or an interface brief. In a new conversation, attach the file or give the agent its path, then adapt this request:

Read .skill-downloads/debugger-mm78noi3/SKILL.md and apply its instructions to this example: [describe a test input]. Identify any missing files, dependencies or access. Produce the result requested by the skill without inventing data or running unreviewed scripts.

Expected result: output matching the skill instructions, or a precise list of missing prerequisites. A read confirmation alone does not validate a first use. If an external resource is unavailable, that path remains untested.

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