CSC Design System Skills & Best Practices
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OpenAI Codex

Codex reads AGENTS.md and skills in .agents/skills. The default combined instruction limit is 32 KiB, so the root file stays short.

Codex skills
AGENTS.md

Root instructions. Nested AGENTS.md files are for a folder, not a second copy of the root.

The same short root file used by Cursor.
.agents/skills/<name>/SKILL.md

Codex loads the body when it selects the skill.

name and description in frontmatter. Detail stays in references/.

Omitted

  • No ~/.codex/config.toml MCP table is generated.
  • agents/openai.yaml is optional and is not created.