Skill YAML
The YAML configuration block in a SKILL.md frontmatter that makes the skill discoverable and invocable by Claude Code.
Skill YAML is the machine-readable contract between a skill and Claude Code. The frontmatter block must include a description field (used for skill matching), and typically includes trigger phrases, category, and version. Claude Code parses this block at session start to build its skill registry. If the YAML is malformed, a common failure is nested double quotes inside double-quoted strings, the skill becomes invisible. The fix is straightforward: use single quotes for trigger phrases inside double-quoted description strings. Validation is a one-liner: python -c "import yaml; yaml.safe_load(open('SKILL.md').read().split('---',2)[1])". Every new skill created via the new-skill-creator skill gets valid YAML by default.
Where it shows up:
Related Terms
Architecture
YAML Frontmatter
The metadata block at the top of SKILL.md files that Claude Code parses to discover and describe ava...
Skills Layer
Skill
A reusable instruction set that encodes a repeatable process. Skills load context, apply methodology...
Skills Layer
New Skill Creator
Guided skill creation that produces a valid SKILL.md with YAML frontmatter, references directory, an...
Foundation
CLAUDE.md
The root instruction file that Claude Code reads at session start, containing your business context,...