Claude Code Skills

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Quick Start ​

Experience your first Claude Code Skill in 5 minutes.

Prerequisites ​

Make sure you have Claude Code installed and available in your terminal.

Hands-on: Debug a Bug with diagnose ​

Scenario ​

You have a Node.js script server.js that crashes occasionally with no error output.

Step 1: Trigger the Skill ​

bash
# In Claude Code
/diagnose server.js crashes occasionally with no error logs

Step 2: Diagnosis Flow ​

Claude Code enters diagnostic mode automatically:

  1. Reproduce — Asks about crash frequency and trigger conditions
  2. Narrow — Inspects code to locate suspicious areas
  3. Hypothesize — Proposes possible causes (e.g., unhandled Promise rejection)
  4. Verify — Adds logging or try-catch to validate the hypothesis
  5. Fix — Provides a fix

Step 3: Apply the Fix ​

Claude gives specific code changes. You confirm and apply.

Hands-on: Write a Function with TDD ​

Step 1: Describe the Requirement ​

/tdd Write a function formatDate that takes a Date and returns 'YYYY-MM-DD'

Step 2: Red-Green-Refactor ​

Claude Code will:

  1. Red — Write the test first
  2. Green — Implement to pass the test
  3. Refactor — Optimize code quality
javascript
// Step 1: Test first
describe('formatDate', () => {
  it('should format date as YYYY-MM-DD', () => {
    expect(formatDate(new Date('2026-01-15'))).toBe('2026-01-15');
  });
});

// Step 2: Implement
function formatDate(date) {
  return date.toISOString().slice(0, 10);
}

Hands-on: Review Code ​

/review Review src/utils/auth.js

Claude Code checks for:

  • Security vulnerabilities
  • Logic issues
  • Performance concerns
  • Readability improvements

Your Next Skill ​

If you want to...Use
Quickly prototype an idea/prototype
Audit security/security-review
Break down a large task/to-issues
Create a PRD document/to-prd
Write a custom Skill/write-a-skill

Going Deeper ​