Will Claude Code actually use your skill?

Paste your SKILL.md. Get an instant check for frontmatter, name, description, trigger phrasing, length, and the mistakes that keep skills from firing.

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// what it checks

Three groups, 14 checks.

Deterministic and offline: the same file always scores the same. These are the same rules behind the header checker on our "skill not triggering" guide, extended to check the whole file.

1
Frontmatter
The --- header parses, closes, has no tabs, and the name field is valid and matches the folder
2
Description
Specific enough to match on, says "use when", no stray colon that breaks the YAML, under the length limit
3
Body and length
Auto-use is on, there are real instructions after the header, and the file is under the 200-line read ceiling

Nine causes of a skill that never fires, with fixes for each: Claude Code skill not triggering? 9 causes and fixes. Starting from zero: how to create a Claude Code skill.