Skill Author

Authoring a cross-agent SKILL.md skill

A skill is a folder with a SKILL.md file inside. The file starts with a YAML frontmatter block (name + description) followed by Markdown instructions the agent loads on demand. Because Claude Code, DeepSeek Harness (dsh), Codex CLI, Gemini CLI, Copilot and Cursor all read this same format, one well-authored skill serves every agent.

Anatomy

my-skill/
├── SKILL.md            # required: frontmatter + instructions
├── references/         # optional: long-form docs the model reads on demand
└── scripts/            # optional: helper scripts the skill may run

---
name: my-skill
description: >-
  One or two sentences: what it does AND when to use it. This is the trigger
  the agent matches against the user's request — write it like a routing rule.
---

# My skill

Step-by-step instructions. Assume a competent engineer; be concrete, not vague.

Rules that decide whether a skill works

1. name must be kebab-case — lowercase letters, digits, hyphens; max 64 chars. Agents reject or mangle other names. aipx normalizes for you, but ship it correct.
2. description is the trigger, not documentation. Bad: "Utilities for working with things." Good: "Summarize YouTube/Bilibili videos and podcasts from a URL. Use when the user pastes a video or audio link."
3. Keep SKILL.md under ~500 lines. Put depth in references/*.md and link to them ("see references/schema.md"). Agents load the body only when the skill triggers; huge bodies waste context and dilute behavior.
4. No nested skills. Discovery scans only the direct children of a skill root — skills/a/SKILL.md is found, skills/a/b/SKILL.md is not.
5. Relative links must stay relative. If SKILL.md references scripts/x.py, the whole folder travels together — never link outside the skill directory.

Where skills live (user roots)

Project-scoped equivalents exist too (e.g. .claude/skills/, .agents/skills/ in the repo). Don't copy by hand — use aipx sync to link one copy into every agent root.

Test before publishing

# does it parse and get discovered?
aipx install ./my-skill --dry-run
aipx install ./my-skill
aipx list

Then open your agent and confirm the skill appears (Claude Code: it shows in the skill list; dsh: / command palette → Skills group).

Publishing checklist

• Repo contains the skill folder at a stable path, e.g. skills/my-skill/
• description states trigger conditions, not just features
• Works from a clean install (aipx install owner/repo#path:/skills/my-skill)
• Add GitHub topics so discovery works: agent-skills, claude-code, dsh-plugin (if it also ships a dsh bundle), deepseek (if DS-related)
• Optional: dual-target packaging — see the dsh-plugin-dev and claude-plugin-dev skills