AGENTS.md - general instructions for Codex/Copilot/OpenCode

  • AGENTS.md in other subfolder with granular rules
  • show examples (bad vs good)
  • project structure
  • set boundaries
    • e.g. do not delete files, write docs in /docs

Best practice
https://github.blog/ai-and-ml/github-copilot/how-to-write-a-great-agents-md-lessons-from-over-2500-repositories/

Custom agents are usually located in ./{cli_tool}/agents

Skills - directory of markdown files

  • skills location are different between copilot vs codex/opencode
.github/skills/<name>/SKILL.md
.agents/skills/

Skill structure

---
name: skill-name
description: When the skill is triggered
---

Skill allow bundle of different structures

  • e.g. a subfolder ./scripts containing scripts to run when the skill is triggered