# Skillcheck

> Validates skill quality — preprocessing safety, frontmatter, line counts, references. Use when checking skills, validating SKILL.md, or when skillcheck, lint skill, or validate skill are mentioned.

- Skill: `outfitter-dev/skillcheck` (Agent Skill, multi-file: 2 files)
- Install (CLI): `npx skillmds@latest add outfitter-dev/skillcheck`
- Raw SKILL.md: https://api.skillmd.com/api/skills/outfitter-dev/skillcheck/raw
- Safety review: pending
- Works with: Claude Code, Claude.ai, OpenAI Codex
- Category: Coding & Dev Tools
- Author: outfitter-dev (https://skillmd.com/u/outfitter-dev)
- Updated: 2026-09-17
- Page: https://skillmd.com/skills/outfitter-dev/skillcheck

---


# Skills Check

Validate skill quality across one or more skill directories.

## Preprocessing Lint

Scan SKILL.md files for `` <bang>`command` `` patterns that trigger Claude Code's preprocessor unintentionally:

!`bun ${CLAUDE_PLUGIN_ROOT}/skills/skillcheck/scripts/lint-preprocessing.ts ${ARGUMENTS:-${CLAUDE_PLUGIN_ROOT}}`

## Interpreting Results

The linter reports:

- File path and line number of each finding
- The matched pattern and surrounding context
- Summary counts (clean, skipped, issues)

### Fixing Issues

| Finding                                         | Fix                                            |
| ----------------------------------------------- | ---------------------------------------------- |
| Unintentional `` <bang>`command` `` in SKILL.md | Replace `!` with `<bang>`                      |
| Intentional preprocessing                       | Add `metadata.preprocess: true` to frontmatter |

### The `<bang>` Convention

SKILL.md files are preprocessed by Claude Code — any `` <bang>`command` `` syntax executes when the skill loads. To safely document or reference the syntax:

- In SKILL.md: use `<bang>` as a stand-in for `!`
- In reference files (references/, EXAMPLES.md): literal `!` is fine and encouraged
- In command files (commands/\*.md): literal `!` is required (that's the feature)

Skills that intentionally preprocess (running scripts at load time) should declare it:

```yaml
metadata:
  preprocess: true
```

## Additional Checks

Beyond preprocessing, verify skill quality with existing tools:

```bash
# Frontmatter validation
bun ${CLAUDE_PLUGIN_ROOT}/scripts/validate-skill-frontmatter.ts <path-to-SKILL.md>

# Full plugin validation
bun ${CLAUDE_PLUGIN_ROOT}/scripts/validate-plugin.ts <plugin-directory>
```

## Deep Validation

After reviewing linter results, spawn the `quartermaster` agent to run deeper validation — frontmatter schema, naming conventions, description quality, line counts, and reference integrity. Pass it the same path argument.

## Quality Checklist

- [ ] No unintentional `` <bang>`command` `` in SKILL.md (this linter)
- [ ] Valid frontmatter (name, description, required fields)
- [ ] SKILL.md under 500 lines
- [ ] All referenced files exist
- [ ] Description has WHAT + WHEN + trigger keywords