What it does. Codex metadata for the skill: display name “Writing for Agents” and short description “Write documents agents consume”. It has no policy block, so Codex may start the skill on its own.
Why it’s here. Codex reads it for its skill picker. The repo’s .agents/invocation.md says every skill carries one and that “It holds Codex UI metadata”. Leaving out the policy block keeps the skill model-invoked, matching its SKILL.md. The CHANGELOG records that the policy line was removed because Codex hid the skill from the model. SKILL.md itself does not refer to this file.