Creating Skills

1. Creating Skills

Agents handle specialized tasks. Skills handle repeatable ones. Now let's look at how to create them.

2. What Are Skills?

A skill is a set of instructions Claude follows whenever you need a consistent process. Define it once, use it across sessions and projects. Where agents are specialists for focused tasks, skills are procedures for repeatable ones: the how rather than the who.

3. Unit Testing as a Skill

The first skill you'll build is for unit testing. A unit test verifies one function in isolation: one input, one expected output, pass or fail. That predictability makes them the foundation of safe refactoring, which means changing code without breaking existing behavior. You'll see that in the next video. For now, you'll codify this process so Claude always follows the same approach.

4. Where Skills Live

Like agents, skills live in .claude but in a skills subdirectory. Personal skills in your home directory apply across all projects. Project skills are scoped to the codebase and shared via git. Each skill gets its own folder with a SKILL.md file as the entry point.

5. SKILL.md Anatomy

Let's look at what goes inside that file. SKILL.md follows the same pattern as agent files: frontmatter with a name and description, followed by markdown instructions. The description is key; it's what Claude uses to decide when to apply the skill automatically. The body is the procedure: clear, sequential steps. One important difference from agents: slash skills lists available skills but doesn't generate them automatically like slash agents does. That said, you can still ask Claude directly to create the skill file for you. The setup is more manual than with agents, but Claude can do the heavy lifting on the content.

6. Creating a Skill Manually

Creating a skill manually takes five steps. Create the directory in your project root, open SKILL.md in your editor, write or paste the frontmatter and instructions, save the file, then start Claude and run slash skills to confirm it's registered and ready to use.

7. The Project So Far

Back to the Music Analytics API. The project now has both a custom agent and a custom skill. The code reviewer agent handles focused review tasks. The unit tests skill handles the testing workflow. In the next video, you'll put the skill to use.

8. When to Use Skills

Reach for a skill when the value is in the process, not the expertise. Unit testing, documentation, security checks — tasks where following consistent steps matters more than having a specialist handle it. Skip skills for one-time tasks or anything that varies significantly each time. When you need a dedicated expert working independently, that's an agent.

9. Skills vs. Agents

The table shows the key differences at a glance: what they are, how they work, where they live, and how to invoke them. But the practical question is: which do you reach for? If you need Claude to follow a consistent process, that's a skill. If you need a dedicated specialist working independently, that's an agent. The table tells you how they differ; that question tells you which to use.

10. Agents + Skills Together

Skills and agents work well together. An agent file can declare which skills it has access to, giving it a defined toolkit. A code reviewer agent, for example, could have the unit tests skill available when it needs to verify changes. As your workflows grow, this combination becomes increasingly powerful.

11. Let's Practice!

Skills extend Claude Code with reusable, consistent workflows. You've seen how to create one — now you'll invoke it on real code. Let's practice.

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