A skill packages a workflow — your steps, rules, and standards — into one reusable, auto-triggering command. Here's what a skill is, how it fires, what goes in a SKILL.md, how to make it reliable, and how to build your first one.
A skill is a folder containing a SKILL.md file: a set of instructions Claude loads on demand. Instead of re-typing the same multi-step process every session, you write it down once and Claude follows it whenever it's relevant. Think of it as turning a workflow you keep explaining into a reusable command.
A prompt is a single instruction that runs once. A skill is a process you keep and reuse — the difference between telling someone what to do today and training them how you work.
Every skill has a description with trigger phrases. Claude reads that description and automatically reaches for the skill when your request matches — you don't have to remember a command, though you can also call it by name. A sharp description is what makes the skill fire at the right moment and stay quiet otherwise.
Two parts. Frontmatter at the top: a name and a description (the trigger). Then the body: the actual steps, the rules to follow, and a clear definition of what 'done' looks like. If the skill should use a script or a template, point at it.
Write it the way you'd brief a smart new teammate who has no context: concrete steps, explicit standards, no guessing.
The best skills end by verifying their own output against your standards before declaring done — dimensions, brand, format, whatever 'correct' means for that task. Baking the check into the skill is how you catch the recurring mistakes before they ship instead of after.
A skill that self-checks beats one that just hopes. This is the single biggest quality upgrade you can make.
Pick a task you repeat weekly. Write the steps you'd give a new hire, save them as SKILL.md with a clear name and description, then enable it in Settings → Capabilities and run it. Iterate the wording until it triggers and behaves the way you want.
The test is simple: if you've explained the same task twice, it should be a skill.
A clean SKILL.md template with frontmatter, steps, standards, and a verification block — ready to fill in for your first skill.