GPT-5 HIGH Reasoning via ChatGPT
Resolved 💬 5 comments Opened Aug 7, 2025 by LuciferMornens Closed Sep 6, 2025
💡 Likely answer: A maintainer (dylan-hurd-oai, contributor)
responded on this thread — see the highlighted reply below.
What version of Codex is running?
codex-cli 0.16.0
Which model were you using?
gpt-5
What platform is your computer?
MacOS
What steps can reproduce the bug?
Please allow reasoning effort HIGH on codex via ChatGPT login. It's set to medium and I speak for all of us.
Paying200$ for medium effort IS NOT IT.
What is the expected behavior?
_No response_
What do you see instead?
_No response_
Additional information
_No response_
5 Comments
This works:
codex -c model_reasoning_effort="high"
PR adding a command for reasoning configuration: https://github.com/openai/codex/pull/2026
Maybe you can refer to the documentation they wrote to add this setting to the configuration file (
~/.codex/config.toml), so you won’t have to enter it manually every time you start.How do I make Codex CLI use GPT5-Thinking? I have the Plus subscription.
Closing this issue as the original report (high reasoning) is now resolved