Debugging Wizard Guide: Usage, Examples, and Best Practices for Beginners

Feb 14, 2026

Cowrie

Dev @ Bswen

Purpose

This post demonstrates how to use the Debugging Wizard skill in Claude Code for systematic error diagnosis and resolution.

Environment

• Claude Code (latest version)
• claude-skills plugin installed
• Terminal access for command execution

What is Debugging Wizard?

Debugging Wizard is a specialized skill in the claude-skills ecosystem that provides structured debugging workflows. When you encounter errors during development, this skill guides you through systematic diagnosis rather than random trial-and-error.

The skill helps with:

• Error analysis and root cause identification
• Step-by-step investigation workflows
• Solution validation and testing
• Learning from debugging sessions

Installation and Setup

First, ensure you have the claude-skills plugin installed:

# Install claude-skills if not already installed
npm install -g claude-skills

Then verify the Debugging Wizard skill is available:

# List available skills
claude-skills list

The Debugging Wizard skill should appear in your skills list. If not, update your skills:

# Update skills to latest version
claude-skills update

Core Usage Patterns

Basic Invocation

When you encounter an error, invoke the skill directly:

/debugging-wizard

Or use natural language triggers:

"I'm getting an error when running my tests"
"Help me debug this authentication issue"
"Something is wrong with my database connection"

When to Use Debugging Wizard

Use this skill when:

• You see error messages you don’t understand
• Your code behaves unexpectedly
• Tests fail without clear reasons
• You need systematic debugging rather than quick fixes

The skill is less useful for:

• Simple syntax errors (IDE catches these)
• Known issues with documented solutions
• Performance optimization (use profiling tools instead)

Practical Examples

Example 1: Debugging a Test Failure

When I run my test suite, I get this error:

npm test

FAIL src/auth/login.test.js
  Auth login
    ✕ should authenticate valid user (145 ms)

  ● Auth login › should authenticate valid user

    expect(received).toBe(expected)

    Expected: true
    Received: false

      23 |     const result = await login(user.email, user.password)
      24 |     const isValid = await validateToken(result.token)
    > 25 |     expect(isValid).toBe(true)
         |                  ^
      26 |   })
      27 |

I invoke Debugging Wizard:

/debugging-wizard

The skill guides me through investigation:

1. Identify the error: Test expects isValid to be true but got false
2. Check the login function: The token generation might be incorrect
3. Examine validateToken: Maybe the validation logic is wrong
4. Test assumptions: Add logging to see what’s actually happening

I add console logs to debug:

// In login function
const token = generateToken(user.id)
console.log('Generated token:', token) // Debug log

// In validateToken function
function validateToken(token) {
  console.log('Validating token:', token) // Debug log
  // ... validation logic
}

When I run the test again:

npm test

Generated token: eyJhbGciOiJIUzI1NiIsInR5cCI6IkpXVCJ9...
Validating token: undefined

The issue is clear: generateToken returns a token but validateToken receives undefined. I check the login function more carefully:

async function login(email, password) {
  const user = await findUser(email)
  if (!user) return null

  const isValid = await bcrypt.compare(password, user.passwordHash)
  if (!isValid) return null

  return {
    token: generateToken(user.id), // Returns object with token
    user: user
  }
}

// But in the test
const result = await login(user.email, user.password)
const isValid = await validateToken(result.token) // Extracts token correctly

The code looks correct. I check the test setup:

beforeEach(async () => {
  await database.clear()
  user = await createUser({
    email: '[email protected]',
    password: 'password123'
  })
})

The issue is in password hashing! When creating the test user, I’m storing plaintext password but the login function compares with bcrypt hash. I fix the test setup:

beforeEach(async () => {
  await database.clear()
  user = await createUser({
    email: '[email protected]',
    password: await bcrypt.hash('password123', 10) // Hash the password
  })
})

Now the test passes:

npm test

PASS src/auth/login.test.js
  Auth login
    ✓ should authenticate valid user (89 ms)

Example 2: Database Connection Error

When I start my application, I get this error:

node server.js

Error: connect ECONNREFUSED 127.0.0.1:5432
    at TCPConnectWrap.afterConnect [as oncomplete] (net.js:1146)
    errno: -111
    syscall: 'connect'
    code: 'ECONNREFUSED'
    address: '127.0.0.1'
    port: 5432

I use Debugging Wizard to investigate:

1. Verify PostgreSQL is running:

# Check if PostgreSQL is running
pg_lsclusters

# Output: (empty - PostgreSQL not running)

2. Start PostgreSQL:

# Start PostgreSQL service
sudo service postgresql start

# Verify it's running
pg_lsclusters
# Output:
# Ver Cluster Port Status Owner    Data directory              Log file
# 15 main     5432 online postgres /var/lib/postgresql/15/main /var/log/postgresql/postgresql-15-main.log

3. Test the connection:

# Test database connection
psql -U postgres -d mydb -c "SELECT 1"

# Output:
#  ?column?
# ----------
#         1

4. Restart the application:

node server.js

Server started on port 3000
Database connected successfully

The key issue was PostgreSQL service not running. Debugging Wizard helped me check the service status systematically rather than guessing.

Best Practices

DO: Recommended Practices

1. Use Debugging Wizard early

When you first see an error, invoke the skill:

"I got this error when running tests: [paste error]. Can you help me debug?"

2. Provide full error context

Include the complete error message, not just the error type:

# Good: Full error with stack trace
Error: Cannot read property 'map' of undefined
    at UserList.render (/src/components/UserList.js:15:20)
    at processComponent (/src/react/process.js:245:12)
    ...

# Bad: Just the error type
Cannot read property 'map' of undefined

3. Show your environment

Include relevant versions and configuration:

package.json

{
  "dependencies": {
    "react": "18.2.0",
    "typescript": "5.1.6"
  }
}

// tsconfig.json
{
  "compilerOptions": {
    "strict": true,
    "target": "ES2020"
  }
}

4. Test your hypotheses

Before applying a fix, verify your understanding:

// Add logging to confirm the issue
console.log('Users data:', users)
console.log('Users type:', typeof users)

// Test the hypothesis
if (!users) {
  console.log('Users is undefined!')
}

DON’T: Common Mistakes

1. Don’t skip investigation

Don’t jump to solutions without understanding the problem:

// Bad: Random fix without understanding
users = users || []

// Better: Investigate why users is undefined
console.log('Fetch result:', result)
console.log('Result.users:', result.users)

2. Don’t ignore error messages

Read the full error message, including stack traces:

# The error message tells you the exact location
Error: Cannot read property 'length' of undefined
    at processUsers (/src/utils/users.js:42:18)
                                  ^^^^^^^^^
    Line 42 is the problem

3. Don’t change multiple things at once

Make one change at a time and test:

// Bad: Change everything at once
// Fix data fetching
// Fix error handling
// Fix UI rendering
// Which change fixed the issue?

// Good: One change, test, then next
// Fix data fetching
// Test
// Fix error handling
// Test
// Fix UI rendering
// Test

4. Don’t rely on console.log forever

Use proper debugging tools:

// Temporary debugging (ok for quick checks)
console.log('User:', user)

// Better: Use debugger
debugger

// Best: Write tests
it('should handle undefined user', () => {
  const result = processUser(undefined)
  expect(result).toBeNull()
})

Related Skills and Resources

Complementary Skills

• tdd-workflow: Test-driven development for preventing bugs
• code-review: Catch issues before they reach production
• security-review: Identify security vulnerabilities during debugging

Official Documentation

• Claude Skills Documentation
• Debugging Wizard Skill Reference
• GitHub Repository

Community Resources

• Claude Skills Discord for community support
• GitHub Issues for bug reports and feature requests
• Example workflows in the repository wiki

Summary

In this post, I showed how to use the Debugging Wizard skill in Claude Code for systematic error diagnosis. The key point is to use structured investigation rather than random trial-and-error when debugging. The skill helps you understand errors deeply, test hypotheses methodically, and learn from each debugging session.

Final Words + More Resources

My intention with this article was to help others share my knowledge and experience. If you want to contact me, you can contact by email: Email me

Here are also the most important links from this article along with some further resources that will help you in this scope:

• 👨‍💻 Claude Skills Official Documentation
• 👨‍💻 Claude Skills GitHub Repository

Oh, and if you found these resources useful, don’t forget to support me by starring the repo on GitHub!

Comments

Tags:

• ai-coding
• ai
• llm
• career

Code Documenter Guide: Usage, Examples, and Best Practices for Beginners

How to Use Fullstack Guardian in Claude Code for Security Development