What it is.
A Skill is a folder. At minimum it holds a SKILL.md file describing what the skill does and when to use it, and it can carry scripts and reference documents alongside.
Loading works by progressive disclosure. Claude reads the short description first, and only pulls in the full instructions and files when a request matches, so a detailed procedure costs nothing on unrelated messages.
What you get is consistency. The same brief, audit, or report comes out the same way whoever asks for it, because the procedure lives in the folder instead of in one person's prompt.
What you get.
- A reusable folder holding one procedure, versionable like code.
- Progressive disclosure, so long instructions cost nothing until they're used.
- Scripts and reference files bundled with the instructions.
- Consistent output whoever triggers the task.
- A format that works across Claude apps and the API.
How to set it up.
Pick a task you have explained to Claude more than twice, since that repetition is the whole reason to build one.
Create the folder and write SKILL.md, starting with what it does and when it should be used.
Keep the description sharp, because that short text is what decides whether the skill gets loaded at all.
Move long reference material into separate files, so the main instructions stay short.
Add any scripts the procedure needs, and say in SKILL.md when to run them.
Test with three requests that should trigger it and two that should not.
Use cases
Package one procedure
Put the instructions and scripts in a folder you can version like code.
Keep long instructions out of the way
Let the detail load only when the task calls for it.
Share a method with the team
Hand over the folder instead of explaining the steps again.
Best for
A prompt you keep pasting
If it lives in a note you copy from, it should be a skill.
Standardizing across a team
Everyone triggering the same procedure removes the variance between people.
Procedures with reference material
Brand rules, schemas, and checklists belong in files, not in a chat message.