Creating Skills

Software Development with Claude Code

Dani Zysman

AI Curriculum Manager @ DataCamp

What Are Skills?

A toolbox with labeled instruction cards

Reusable instructions Claude follows on demand
Define once, use everywhere
Invoked with /skill-name or automatically

Unit Testing as a Skill

Unit test concept showing function tested in isolation

Where Skills Live

Personal skills (all projects):

~/.claude/
  /skills/
    /my-skill/
      SKILL.md

Project skills (this project):

project/
  /.claude/
    /skills/
      /unit-tests/
        SKILL.md

SKILL.md Anatomy

___
# SKILL.md
name: unit-tests
description: Generate pytest unit tests for Python functions
___

When asked to write unit tests:
1. Identify the function's inputs and outputs
2. Write tests for normal cases first
3. Add edge cases (empty input, invalid data)
4. Use descriptive test names
5. Run pytest to verify tests pass

Frontmatter = name + description | Body = step-by-step instructions

Creating a Skill Manually

Recipe to create a skill:

In your project root directory create a new one mkdir -p .claude/skills/unit-tests
Open the file: code .claude/skills/unit-tests/SKILL.md (or editor of your choice)
Write or paste the frontmatter and instructions
Save the file
Start claude and check if your skill is available with /skills

The Project So Far

music-analytics-api/
  app.py
  routes.py
  models.py
  CLAUDE.md
  .claude/
    agents/
      code-reviewer.md
    skills/              # <- Skills folder
      unit-tests/
        SKILL.md

When to Use Skills

Good for skills:
- Repetitive workflows with consistent steps
- Team coding standards to enforce
- Multi-step workflows that need to be reproducible
- Patterns that should be followed every time

Not good for skills:
- One-time tasks
- Simple questions about code
- Tasks that vary significantly each time
- Quick file lookups

Skills vs. Agents

Feature	Skills	Agents
What they are	Instructions Claude follows	Specialized assistants
How they work	Claude executes the steps	Agent works independently
Location	`.claude/skills/`	`.claude/agents/`
Invocation	`/skill-name` or automatic	`@agent-name` or automatic

Both extend Claude Code - use skills for workflows, agents for expertise

Agents + Skills Together

Agent file declaring skills it has access to

Let's Practice!

Software Development with Claude Code