OpenAI Codex CLI: Lightweight coding agent that runs in your terminal

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.

Claude Code still feels superior. o4-mini has all sorts of issues. o3 is better but at that point, you aren't saving money so who cares.

I feel like people are sleeping on Claude Code for one reason or another. Its not cheap, but its by far the best, most consistent experience I have had.

"gemini 2.5 pro exp" is superior to Claude Sonnet 3.7 when I use it with Aider [1]. And it is free (with some high limit).

[1]https://aider.chat/

Compared to cline aider had no chance, the last time I tried it (4 month ago). Has it really changed? Always thought cline is superior because it focuses on sonnet with all its bells an whistles. While aider tries to be an universal ide coding agent which works well with all models.

When I try gemmini 2.5 pro exp with cline it does very well but often fails to use the tools provided by cline which makes it way less expensive while failing random basic tasks sonnet does in its sleep. I pay the extra to save the time.

Do not get me wrong. Maybe I am totally outdated with my opinion. It is hard to keep up these days.