# Skill Validator

> Validate Claude Code skill files (SKILL.md) against Anthropic's structural requirements. Use this skill whenever the user asks to validate, lint, check, or verify a skill file or skill structure. Triggers on "validate skill", "lint skill", "check skill", "verify SKILL.md", "does my skill meet requirements", or any request to confirm a skill is correctly structured before publishing or importing.

- Skill: `fyzel/skill-validator` (Agent Skill, multi-file: 3 files)
- Install (CLI): `npx skillmds@latest add fyzel/skill-validator`
- Raw SKILL.md: https://api.skillmd.com/api/skills/fyzel/skill-validator/raw
- Safety review: pending
- Works with: Claude Code, Claude.ai, OpenAI Codex
- Category: Coding & Dev Tools
- Author: Fyzel (https://skillmd.com/u/fyzel)
- Updated: 2026-09-17
- Page: https://skillmd.com/skills/fyzel/skill-validator

---


# Skill Validator

Validates `SKILL.md` files in the `skills/` directory against Anthropic's requirements using `skills/skill-validator/scripts/validate-skills.py`.

## What it checks

- `name` field present and matches the skill's directory name
- `description` field present
- No XML tags (`<...>`) in `description` — Claude Code rejects these on load
- Combined `description` + `when_to_use` length ≤ 1,536 characters
- Frontmatter parsed via PyYAML (handles block scalars correctly)
- Packaging simulation writes `skills/<name>/.test/<name>.skill` and reports archive size

## Run

Validate all skills:

```sh
# Windows
.venv/Scripts/python skills/skill-validator/scripts/validate-skills.py

# Linux / macOS
.venv/bin/python skills/skill-validator/scripts/validate-skills.py
```

Validate one skill by name:

```sh
# Windows
.venv/Scripts/python skills/skill-validator/scripts/validate-skills.py <skill-name>

# Linux / macOS
.venv/bin/python skills/skill-validator/scripts/validate-skills.py <skill-name>
```

Skip packaging simulation:

```sh
# Windows
.venv/Scripts/python skills/skill-validator/scripts/validate-skills.py --no-package

# Linux / macOS
.venv/bin/python skills/skill-validator/scripts/validate-skills.py --no-package
```

Exit code `0` = all pass. Exit code `1` = one or more failures.

## Setup

Requires Python in `.venv`:

```sh
python -m venv .venv
pip install -r requirements.txt
```