I tried one task head-to-head with Codex o4-mini vs Claude Code: writing documentation for a tricky area of a medium-sized codebase.

Claude Code did great and wrote pretty decent docs.

Codex didn't do well. It hallucinated a bunch of stuff that wasn't in the code, and completely misrepresented the architecture - it started talking about server backends and REST APIs in an app that doesn't have any of that.

I'm curious what went so wrong - feels like possibly an issue with loading in the right context and attending to it correctly? That seems like an area that Claude Code has really optimized for.

I have high hopes for o3 and o4-mini as models so I hope that other tests show better results! Also curious to see how Cursor etc. incorporate o3.

related demo/intro video: https://x.com/OpenAIDevs/status/1912556874211422572

this is a direct answer to claude code which has been shipping furiously: https://x.com/_catwu/status/1903130881205977320

and is not open source; there are unverified comments that they have DMCA'ed decompilations https://x.com/vikhyatk/status/1899997417736724858?s=46

by total coincidence we're releasing our claude code interview later this week that touches on a lot of these points + why code agent CLIs are an actually underrated point in the SWE design space

(TLDR you can use it like a linux utility - similar to @simonw's `llm` - to sprinkle intelligence in all sorts of things like CI/PR review without the overhead of buying a Devin or a Copilot SaaS)

if you are a Claude Code (and now OAI Codex) power user we want to hear use cases - CFP closing soon, apply here https://sessionize.com/ai-engineer-worlds-fair-2025

These days, I usually paste my entire (or some) repo into gemini and then APPLY changes back into my code using this handy script i wrote: https://github.com/asadm/vibemode

I have tried aider/copilot/continue/etc. But they lack in one way or the other.

Fingers crossed for this to work well! Claude Code is pretty excellent.

I’m actually legitimately surprised how good it is, since other coding agents I’ve used before have mostly been a letdown, which made me only use Claude in direct change prompting with Zed (“implement xyz here”, “rewrite this function with abc”, etc), so very hands-on.

So I’ve went into trying out Claude Code rather pessimistically, and now I’m using it all the time! Sure, it ends up costing a bunch, but it’s easy to justify $15 for a prompting session if the end result is a mostly complete PR, done much faster.

All that is to say - competition is good, fingers crossed for codex!

This is pretty neat! I was able to use it for few use cases where it got it right the first time. The ability to use a screenshot to create an application is nice for rapid prototyping. And good to see them open sourcing it unlike claude.