---
url: /rules/skills/skill-frontmatter-unknown-keys.md
description: Unknown key in SKILL.md frontmatter
---

# skill-frontmatter-unknown-keys

## Rule Details

SKILL.md frontmatter supports a specific set of known keys: name, description, version, tags, allowed-tools, model, context, agent, argument-hint, disable-model-invocation, user-invocable, hooks, license, compatibility, and metadata. This rule detects any top-level keys that are not in this set. Unknown keys are silently ignored at runtime, which means typos in field names go unnoticed and the intended configuration never takes effect.

### Incorrect

Frontmatter with a typo in a key name

```yaml
---
name: deploy
description: Deploys the application
contxt: fork
---
```

Frontmatter with a completely unknown key

```yaml
---
name: deploy
description: Deploys the application
author: Jane Doe
---
```

### Correct

Frontmatter using only recognized keys

```yaml
---
name: deploy
description: Deploys the application
allowed-tools:
  - Bash
---
```

## How To Fix

Valid keys: name, description, version, tags, allowed-tools, model, context, agent, argument-hint, disable-model-invocation, user-invocable, hooks, license, compatibility, metadata. Check for typos in your field names.

## Options

This rule does not have any configuration options.

## Related Rules

* [`skill-description`](/rules/skills/skill-description)
* [`skill-allowed-tools`](/rules/skills/skill-allowed-tools)

## Resources

* [Rule Implementation](https://github.com/pdugan20/claudelint/blob/main/src/rules/skills/skill-frontmatter-unknown-keys.ts)
* [Rule Tests](https://github.com/pdugan20/claudelint/blob/main/tests/rules/skills/skill-frontmatter-unknown-keys.test.ts)

## Version

Available since: v0.3.0