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Validate Claude Code skills against the agentskills specification. Catches structural, semantic, and naming issues before users do.
Passed 19 of 22 test cases with the skill, and 6 of 22 without it.
and 13 more in the full report
15 fixed7 passed either way3 still failing0 broke
Tokens, turns and time describe resource use, not a dollar price.
One of 15 test cases the skill fixed. Same model, same prompt, with and without the skill.
An oversized SKILL.md file exceeds recommended body length limits at `./skills/monolith/SKILL.md`. Which category check evaluates line count?
| Checked | Without skill | With skill |
|---|---|---|
| Evaluates line count under Body 2.x checks | Missed | Passed |
The instructions your model reads when the skill loads.
Validate SKILL.md files against the agentskills specification and Anthropic best practices. Catches structural errors, semantic contradictions, naming anti-patterns, and quality gaps in a single read-only pass.
Read the target SKILL.md file and extract YAML frontmatter.
Apply all Free tier checks in order:
| Category | Checks | What it catches |
|---|---|---|
| Structure (1.x) | Name format, description WHAT+WHEN, allowed-tools, categories, XML injection | Malformed frontmatter, missing fields |
| Body (2.x) | Line count, hardcoded paths, stale dates, empty sections, deprecated syntax, MCP tool qualification | Content quality issues |
| Naming (3.x) | Vague terms, single-word names, gerund suggestions | Poor discoverability |
| Semantic (4.x) | Contradictions, ambiguous terms, missing output format, wisdom/platitudes, misplaced triggers | Logical inconsistencies |
| Quality (8.x) | Examples, error handling, triggers, output format, prerequisites, negative triggers | Strengths (positive patterns) |
Calculate overall score (0-100). Penalties: critical = -20, warning = -5, suggestion = -1.
Return structured results: score, grade (Excellent/Good/Needs Work/Poor), issue list with check IDs, line numbers, messages, and fix suggestions.
test cases passed, vs 6 / 22 without
Published skills whose descriptions closely match this one, with their headline benchmark lift.
More skills from the same source and nearby in the registry, with their headline benchmark lift.