Writing Skills

Use after RETRO identifies a pattern worth formalizing as a reusable skill.

Skill Folder Structure

skills/{skill-name}/
├── SKILL.md              ← core instructions, ≤200 lines
├── references/           ← detailed docs, loaded on demand
│   └── *.md
├── scripts/              ← executable tools, only output enters context
│   └── *.sh / *.py
└── assets/               ← templates, blank forms
    └── *.md

Required SKILL.md Frontmatter

---
name: skill-name              # kebab-case, ≤64 chars, becomes /skill-name
description: >                # ≤200 chars — ONLY thing read before triggering
  When this skill activates. What it produces. Key trigger words or contexts.
  Make this searchable. Be specific about when to use vs not use.
allowed-tools: Read Write Bash  # optional — restrict available tools
---

The 200-Line Rule

SKILL.md must stay under 200 lines. If content exceeds it:

1. Identify the long section (usually examples or detailed reference)
2. Move it to references/{descriptive-name}.md
3. Replace with: See references/{name}.md for [brief description]

What stays in SKILL.md: the protocol (what to do, in what order) What goes to references/: examples, full checklists, edge cases, templates What goes to scripts/: validation, detection, generation logic What goes to assets/: blank templates the user copies

Writing Good Descriptions

The description is ALL the agent reads before deciding to load this skill.

Bad: "A skill for debugging code." Good: "Hypothesis-driven debugging. Triggers on debug, error, broken, failing. Forces explicit hypothesis before fix. Prevents guess-and-check debugging."

Promoting from Draft

Draft skills go to .ohc/skills/{name}.md (single file, informal). Promoted skills go to skills/{name}/SKILL.md (full folder structure).

ohc skill draft {name}    # scaffold folder + template
ohc skill promote {name}  # move draft to skills/ folder

See references/skill-spec.md for the complete Anthropic skill specification. See references/frontmatter-guide.md for all frontmatter fields.