---

name: skill-linter description: Validate skills against agentskills.io specification. Use when adding new skills to the marketplace, reviewing skill PRs, checking skill compliance, or running quality gates on skills. Validates frontmatter fields (name, description, license, compatibility, metadata, allowed-tools), directory naming, line limits, and structure. allowed-tools: Bash Read Glob Grep

Skill Linter

When to Use

• Adding new skills to the marketplace
• Reviewing skill PRs
• Running quality gates before merge
• Checking existing skills for compliance

Validation Rules

Required Frontmatter

Field	Constraints
name	1-64 chars, lowercase alphanumeric + hyphens, no leading/trailing/consecutive hyphens, must match parent directory name
description	1-1024 chars, non-empty, should include keywords for discoverability

Optional Frontmatter

Field	Constraints
license	Short license name or file reference
compatibility	1-500 chars, environment requirements
metadata	Key-value pairs (string values only)
allowed-tools	Space-delimited tool list

Structure Requirements

Rule	Requirement
Directory name	Must match name field exactly
SKILL.md	Required, must exist
Line limit	Max 500 lines in SKILL.md
Subdirectories	Only scripts/, references/, assets/ allowed

Content Quality Rules

Rule	Requirement
No ASCII art	Box-drawing characters (─│┌┐└┘├┤┬┴┼), arrows (↑↓←→↔), and decorative diagrams waste tokens. LLMs tokenize character-by-character, not visually. Use plain lists or tables instead.
No decorative quotes	Inspirational quotes or attributions ("As X said...") have no functional value for LLM execution.
No persona statements	"You are an expert..." wastes tokens. Use Audience: / Goal: framing instead.
Functional content only	Every line should improve LLM behavior. Ask: "Does this help Claude execute better?"

Audience/Goal Framing (Required)

Replace persona roleplay with audience-focused framing:

❌ Bad (persona):

You are an expert software engineer with deep expertise in testing.
Your role is to analyze code and generate thorough test coverage.

✅ Good (audience/goal):

**Audience:** Developers needing test coverage for new or changed code.

**Goal:** Generate comprehensive tests based on specified test type and framework.

Rationale: "Explain X for audience Y" yields better-tailored outputs than "Act as persona Z".

ASCII Art Detection Pattern:

[─│┌┐└┘├┤┬┴┼╭╮╯╰═║╔╗╚╝╠╣╦╩╬↑↓←→↔⇒⇐⇔▲▼◄►]{3,}

Files matching this pattern should be flagged for review.

Name Pattern

^[a-z][a-z0-9]*(-[a-z0-9]+)*$

Valid: my-skill, skill1, api-v2-handler Invalid: -skill, skill-, my--skill, MySkill, my_skill

Usage

Validate Single Skill

./scripts/validate-skill.sh path/to/skill-name

Validate All Marketplace Skills

for skill in plugins/*/skills/*/; do
  ./scripts/validate-skill.sh "$skill"
done

CI Integration

Add to pre-commit hook or CI pipeline:

- name: Lint Skills
  run: |
    for skill in plugins/*/skills/*/; do
      .claude/skills/skill-linter/scripts/validate-skill.sh "$skill" || exit 1
    done

Validation Script

The linter script at scripts/validate-skill.sh performs these checks:

1. Directory exists with SKILL.md file
2. Frontmatter present with YAML delimiters
3. Name field valid - pattern, length, matches directory
4. Description field valid - present, length constraints
5. Optional fields valid - if present, match constraints
6. Line count - under 500 lines
7. Subdirectory names - only allowed directories
8. No ASCII art - detects box-drawing characters and decorative diagrams

Error Codes

Code	Meaning
0	All validations passed
1	Missing SKILL.md
2	Invalid frontmatter
3	Name validation failed
4	Description validation failed
5	Optional field validation failed
6	Line limit exceeded
7	Invalid subdirectory
8	ASCII art detected (warning)

Example Output

Validating: plugins/majestic-tools/skills/brainstorming

[PASS] SKILL.md exists
[PASS] Frontmatter present
[PASS] Name 'brainstorming' valid (12 chars)
[PASS] Name matches directory
[PASS] Description valid (156 chars)
[PASS] Line count: 87/500
[PASS] Subdirectories valid

Result: ALL CHECKS PASSED

Spec Reference

Based on agentskills.io/specification:

• Progressive disclosure - Metadata ~100 tokens at startup, full content <5000 tokens when activated
• Reference files - Keep one level deep from SKILL.md
• Token budget - Main SKILL.md recommended under 500 lines