Chapter 17: Write Your First Claude Code SKILL.md
In this chapter, you'll write your first real Claude Code Skill from scratch by building a disk space audit that reads the live system state, applies custom thresholds, and produces a consistent summary every time.
In the previous chapter, you learned what Skills are, how the SKILL.md format works, and when it makes more sense to create a Skill instead of adding more instructions to CLAUDE.md.
Now it's time to build your first real Skill: a disk space audit that checks your system's current disk usage, applies the limits you define, and generates a clear, consistent summary in plain English every time you run it.
A disk space audit is a great first Skill because it's a task you'll likely perform regularly. It also shows how a Skill can automate a repeatable task while keeping the output easy to read and consistent.
The instructions are simple enough to write in about 10 minutes, but useful enough that you'll keep using the Skill whenever you want to check your system's storage.
By the end of this chapter, you'll have a working Skill installed, test it to make sure it works, and understand a practical pattern you can use to create Skills for your own everyday tasks.