How To Build Skills — Development skill for Claude Code

How to Build Skills

[](https://github.com/Iknowitsimpossible/how-to-build-skills/actions/workflows/ci.yml)

A hands-on course in writing **Agent Skills**: folders of instructions that teach an AI coding agent to follow a repeatable process for your tasks. The [open format](https://agentskills.io) is portable; tools, permissions, dependencies, and discovery behavior still depend on the agent.

You'll get eight short lessons, three working example skills (from one file to a real published skill), two templates, and a validator that checks structure and YAML while separating errors from authoring suggestions.

What is a skill?

A skill is a folder with a `SKILL.md` file in it:

---
name: commit-message
description: Writes a git commit message for the staged changes. Use when the user says "write a commit message" or "commit this". Do NOT use for PR descriptions.
---

# Commit Message

## Instructions
1. Run `git diff --staged`.
2. Write a subject line of at most 50 characters, in the imperative mood...

Agents typically use available skills' `name` and `description` to decide what to load. Discovery and explicit invocation vary by platform; test both in the agents you support. So you explain your process once, and the agent applies it whenever it's relevant.

Choose your path

**Build your first skill:** follow the quickstart, then [plan a use case](lessons/02-plan-use-cases.md). Start with one file.

**Improve an existing skill:** begin with [behavioral testing](lessons/06-testing.md), then [adjust its level of detail](lessons/04-instructions.md#choose-how-much-to-prescribe).

What you will learn to change

An illustrative README review:

**Vague instruction:** “Make the README better.”

**Unhelpful result:** “Add a screenshot and improve setup.” The author still has to work out what to edit.

**Better instruction:** Identify each edi