Writing Skills

A skill is a debugging tool for agent behaviour, not documentation. Everything here reduces to one question:

What does the agent get wrong without this skill — and how will I know it's fixed?

A skill earns every token only by changing what the agent does. A sentence that doesn't change behaviour costs context in every future session and earns nothing. When any decision below feels unclear, return to the question.

Is a skill the right tool?

Three mechanisms overlap; pick by trigger, not habit: