Skill quality linter

Skill Quality Linter

When to Use

• Before publishing a new skill to a registry
• Reviewing a skill PR
• Auditing existing skill quality
• Setting up CI for a skill repository

Lint Checks

1. Frontmatter (Required Fields)

Field	Required	Format
name	YES	kebab-case, matches directory name
description	YES	1 line, max 250 chars, starts with verb
version	YES	Semver (X.Y.Z)
last-updated	YES	YYYY-MM-DD, not in future
platforms	YES	Array of known platform names
license	YES	Valid SPDX identifier
dependencies	RECOMMENDED	Object with mcp, skills, apis, data
update_sources	RECOMMENDED	Array with url + check_frequency
language	RECOMMENDED	ISO 639-1 (en, fr, etc.)
geo_relevance	RECOMMENDED	Array (global, fr, eu, africa, etc.)
category	RECOMMENDED	Matches parent directory name
priority	OPTIONAL	critical, high, medium, low

2. Structure

Check	Rule
Starts with ---	Valid YAML frontmatter
Has # Title	H1 heading after frontmatter
Has ## When to Use	Trigger conditions documented
Has ## What This Skill Does NOT Do	Limitations section present
No H1 other than title	Single H1 only
Sections use H2 (##)	Consistent hierarchy

3. Size Budget

Metric	Limit	Rationale
SKILL.md lines	< 800	ETH Zurich: more = worse perf
SKILL.md tokens	< 2500	Context window budget
SKILL.md + references/	< 3000 tokens	Total load budget
references/ file count	< 5	Keep focused

4. Portability

Check	Rule
No tool-specific syntax	No Read, Write, Bash, Edit references
No platform-specific imports	No import, require, from in instructions
Natural language instructions	Steps readable by any agent
Graceful degradation	"If terminal available... otherwise..." pattern

5. Freshness

Age	Status
< 60 days	PASS
60-90 days	WARN — review needed
> 90 days	FAIL — must update before use

6. Naming

Check	Rule
Directory name	kebab-case, no uppercase
name field	Matches directory exactly
description	Starts with action verb (Guide, Build, Detect, Generate...)
No emoji in name/description	Plain text only

Output Format

LINT: {skill-name}
Status: PASS | WARN | FAIL

[PASS] Frontmatter: all required fields present
[PASS] Structure: all sections present
[WARN] Size: 2800 tokens (approaching 3000 limit)
[PASS] Portability: no platform-specific syntax
[PASS] Freshness: 5 days old
[PASS] Naming: matches conventions

Verdict: PASS (1 warning)

What This Skill Does NOT Do

• Does not check factual accuracy of content
• Does not validate referenced URLs (use separate check)
• Does not scan for security issues (see skill-security-audit)
• Does not auto-fix issues (reports only)