aigent-validator

name	aigent-validator
description	Validates AI agent skill definitions (SKILL.md files) against the Anthropic agent skill specification. Checks frontmatter fields (name, description), format rules, and body guidelines. Use when validating skills, checking SKILL.md files, or reviewing skill definitions for spec compliance.
allowed-tools	Bash(aigent validate *), Bash(command -v *), Read, Glob
argument-hint	[skill-directory-or-file]

Skill Validator

Setup

Check if aigent is available:

command -v aigent

With aigent CLI

If aigent is on $PATH, use the CLI for authoritative validation:

aigent validate <skill-directory>

Exit code 0 means valid. Non-zero means errors. Warnings are printed but do not cause failure.

If a SKILL.md file path is provided instead of a directory, aigent automatically resolves to the parent directory.

Without aigent CLI

If aigent is not available, validate manually by reading the SKILL.md and checking these rules:

Frontmatter checks

1. File starts and ends with --- delimiters
2. name field: present, string, ≤ 64 chars, lowercase + hyphens + numbers only, no consecutive hyphens, no leading/trailing hyphens, no reserved words ("anthropic", "claude"), no XML tags, matches directory name
3. description field: present, string, non-empty, ≤ 1024 chars, no XML tags

Optional field checks

4. compatibility: if present, string, ≤ 500 chars
5. license: if present, string
6. allowed-tools: if present, string

Body checks

7. Body ≤ 500 lines (warning, not error)

Report format

Report each issue on its own line. Prefix warnings with "warning: ".