Writing Skills

Skills follow the agentskills.io specification. They use YAML frontmatter for metadata and Markdown for the prompt.

Directory Structure

Create a custom skill in one of the conventional directories:

Skill locations

.agents/skills/api-review/SKILL.md
.warden/skills/api-review/SKILL.md
.claude/skills/api-review/SKILL.md

SKILL.md Format

.agents/skills/api-review/SKILL.md

---
name: api-review
description: Review API changes for compatibility and contract issues
allowed-tools: Read Grep Glob
---

Review API changes for:
- Breaking response shape changes
- Missing pagination on list endpoints
- Inconsistent error response formats
- New endpoints without authentication checks

Focus on issues in the changed code. For each issue found, report:
- The specific contract or compatibility risk
- Why it is a problem
- How to fix it

Frontmatter

namestring

Skill identifier referenced in triggers and CLI.

descriptionstring

Brief description of what the skill does.

allowed-toolsstring

Space-separated tool names.

Tools

Available tool names include Read, Grep, Glob, Edit, Write, Bash, WebFetch, and WebSearch.

Most review skills only need Read, Grep, and Glob. Warden restricts execution to read-only tools during analysis, regardless of what the skill declares.

What Makes a Good Skill

• Specific scope: one concern per skill.
• Clear criteria: define what counts as an issue and how severe it is.
• Actionable output: findings should say how to fix the problem.
• Examples: include good and bad code when the distinction is subtle.