OpenAI are quietly adopting skills, now available in ChatGPT and Codex CLI

Posted by simonw 3 days ago

OpenAI are quietly adopting skills, now available in ChatGPT and Codex CLI(simonwillison.net)

572 points | 318 commentspage 2

mehdibl 3 days ago|

This is killing me with complexity. We had agents.md and were supposed to augment the context there. Now back to cursor rules and another md file to ingest.

simonw 2 days ago||

MCPs feel complicated. Skills seem to me like the simplest possible design for a mechanism for adding extra capabilities to an existing coding agent.

febed 2 days ago||

Can skills completely replace MCPs? For example, can a skill be configured to launch my local Python program in its own venv. I don’t want Claude to spend time spinning up a runtime

simonw 2 days ago||

Skills only work if you have a code environment up and running and available for a coding agent to execute commands in.

You can absolutely have a skill that tells the coding agent how to use Python with your preferred virtual environment mechanism.

I ended up solving that in a slightly different way - I have a Claude hook that spits attempts to run "python" or "python3" and returns an error saying "use uv run instead".

delaminator 2 days ago|||

I tell Claude to make its own skills. “Which part of this task is worth making a skill for, use your skill making skill to do it”

baq 2 days ago||

If we aren’t in the take off phase, I don’t know where we are

rafaquintanilha 2 days ago||

Skills are just pointers to context so you don't need to load all of them upfront, it is as simple as that. By the way cursor rules is effectively the same as agents.md.

dsiegel2275 2 days ago||

This is great that Codex CLI is adding skills - but it would be far more useful if the CLI looked first in the project (the directory where I've launched codex) `.codex/skills` directory and THEN the home directory .codex dir. The same issue exists for prompts.

Fannon 2 days ago||

This is nice, but that it goes into its vendor specific .codex/ folder is a bit of a drag.

I hope such things will be standardized across vendors. Now that they founded the Agentic AI Foundation (AAIF) and also contributed AGENTS.md, I would hope that skills become a logical extension of that.

https://www.linuxfoundation.org/press/linux-foundation-annou...

https://aaif.io/

lynx97 2 days ago||

@simonw: Any particular reason you stopped releasing "llm" regularily? I believe the last release was done in summer. Neither gpt-5.1 nor gpt-5.2 have been added. Are you about to give up on that project? Is it time to search for another one?

I also have an open issue since months, which someone wrote a PR for (thanks") a few weeks ago.

Are you still comitted to that project?

simonw 2 days ago|

I shipped a new release yesterday - https://llm.datasette.io/en/stable/changelog.html#v0-28 but yeah, the last core release before that was in August. I've been pushing out plugin releases for it though, for new models from Gemini and Anthropic and others.

Honestly the main problem has been that LLM's unique selling point back in 2024 was that it was the only tool taking CLI access to LLMs seriously. In 2025 Claude Code and Codex CLI etc all came along and suddenly there's not much unique about having a CLI tool for LLMs any more!

There's also a major redesign needed to the database storage and model abstraction layer in order to handle reasoning traces and more complex tool call patterns. I opened an issue about that here - it's something I'm stewing on but will take quite some work to get right: https://github.com/simonw/llm/issues/1314

I've been spending more of my time focusing on other projects which make use of LLM, in particular Datasette plugins that use the asyncio Python library: https://llm.datasette.io/en/stable/python-api.html#async-mod...

I expect those to drive some core improvements pretty soon.

jstummbillig 2 days ago||

Is there a fundamental difference between a skill and a tool or could I just make a terse skill and have that be used in the same way as a tool?

Imanari 2 days ago|

I think a tool call can be thought of as special type of reply where it’s contents are parsed and an actual function is called. A skill is more of a dynamic context-enrichment.

rokoss21 2 days ago||

This is a clever abstraction. Reminds me of how tool_use worked in earlier Claude versions - defining a schema upfront and letting the model decide when to call it.

Has anyone tested how well this works with code generation in Codex CLI specifically? The latency on skill registration could matter in a typical dev workflow.

sorcercode 2 days ago||

this makes sense and as usual great eye by Simon. progressive disclosure is such a powerful concept, that every other tool is going to start adopting it. we've personally had such great results adopting it, especially for performing high quality large migrations.

I wrote about this but I'm certain that eventually commands, MCPs etc will fade out when skills is understood and picked up by everyone

https://kau.sh/blog/claude-skills/

bzmrgonz 3 days ago||

It is interesting that they are relying on visual reading for document ingestion instead of OCT. Recently I read an article which says Handwriting recognition has matured, and I'm beginning to think this is the approach they are takingwirh HAndwiting recognition.

jaco6 2 days ago|

[dead]

blcknight 2 days ago||

I like Anthropic’s plugin system. I wish everyone would standardize on it instead of everyone having a billion different ways to do slash commmands, skills, etc.

sandspar 2 days ago|

Totally unrelated but what’s up with the word “quietly”? Its usage seems to have gone up 5000%, essentially overnight, as if there’s a contagion. You see the word in the New York Times, in government press releases, in blogs. ChatGPT 5.1 itself used the word in almost every single response, and no amount of custom instructions could get it to stop. That “Google Maps of London restaurants” article that’s going around not only uses the word in the headline, but also twice in the closing passage alone, for example. And now Simon, who’s an excellent writer with an assertive style, has started using it in his headlines. What’s the deal? Why have so many excellent writers from a wide range of subjects suddenly all adopted the same verbal tic? Are these writers even aware that they’re doing it?

simonw 2 days ago||

Huh! I had not noticed that trend at all.

Here's the Google Maps article: https://laurenleek.substack.com/p/how-google-maps-quietly-al... - note that the Hacker News title left that word out: https://news.ycombinator.com/item?id=46203343

It's possible I was subconsciously influenced by that article (I saw it linked from a few places yesterday I think), but in this case I really did want to emphasize that OpenAI have started doing this without making any announcements about it at all, which I think is noteworthy in its own right.

(I'm also quite enjoying that this may be the second time I've leaked the existence of skills from a major provider - I wrote about Anthropic's skills implementation a week before they formally announced it: https://simonwillison.net/2025/Oct/10/claude-skills/)

sandspar 2 days ago||

It’s definitely a useful word! Modern tech rollouts often do happen without fanfare. And the word alerts readers to a kind of story shape. So I can see why people use it! Its usage reminds me of when competitive video games develop a new meta, a new powerful technique. There follows a short period where everyone spams the technique over and over. Eventually people figure out a counter and the meta quietly disappears. (Couldn’t help myself!)

sunaookami 2 days ago||

Maybe you fell into https://en.wikipedia.org/wiki/Frequency_illusion ? :D

sandspar 2 days ago||

Probably in part, yes! Since it’s a pet peeve, I must be making extra special note of it every time I see it. So it’s probable that I’m overweighting it!

That being said I’m quite sure that it’s being used more frequently recently. For example, I read a shortish 2000-word article yesterday that uses the word “quietly” four times. And ChatGPT 5.1 used it in most of its responses. Also I’d expect that the frequency illusion wears off quite quickly, whereas I’ve noticed “quietly” for some time and the feeling doesn’t seem to be wearing off. Maybe you’ll start to notice it now too!

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