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Codex Issues / #10573

Specify that a skill cannot be invoked implicitly

Resolved 💬 3 comments Opened Feb 4, 2026 by your-diary Closed Feb 4, 2026
💡 Likely answer: A maintainer (etraut-openai, contributor) responded on this thread — see the highlighted reply below.

I used to utilize custom prompts.

They are very useful because I can inject them explicitly only when I want to; I have full control over them.

Now custom prompts are deprecated and the Codex team suggests the use of skills (link1, link2):

Custom prompts are deprecated. Use skills for reusable instructions that Codex can invoke explicitly or implicitly.

But, as far as I know, skills may be invoked implicitly (link):

Implicit invocation: Codex can decide to use an available skill when your task matches the skill’s description.

Would skills really work in place of deprecated custom prompts? Is it possible to define skills which will never be invoked implicitly?

View original on GitHub ↗

3 Comments

etraut-openai contributor · 6 months ago

If you're concerned about implicit invocation, you could:

  1. Keep the skill description very general so it's unlikely to be invoked implicitly
  2. Add something like "do not use until I explicitly ask" to the skill description
  3. Add something to that effect in your AGENTS.md file ("do not invoke the $auto-destruct skill unless I explicitly request it")
your-diary · 6 months ago

Thank you for the reply and answering my question!

I understand there is (perhaps currently?) no way to systematically disable implicit invocation.

As instructions such as AGENTS.md are often ignored (I encounter this situation multiple times a day and there are many similar issues opened) and I don't want to worry about implicit invocations at all (I don't have to when I use custom prompts), I'll stick to custom prompts for now, until the feature is hard-deprecated and removed.

Please also note project-local skills are supported and such skills are often written by others (e.g. coworkers). I don't want to bother them by always saying "please write skills in a way that they will never be implicitly invoked because I personally don't want/like implicit invocations".

your-diary · 6 months ago

Just added a feature request related to this: