With not much more effort you can get a much better review by additionally concatenating the touched files and sending them as context along with the diff. It was the work of about five minutes to make the scaffolding of a very basic bot that does this, and then somewhat more time iterating on the prompt. By the way, I find it's seriously worth sucking up the extra ~four minutes of delay and going up to GPT-5 high rather than using a dumber model; I suspect xhigh is worth the ~5x additional bump in runtime on top of high, but at that point you have to start rearchitecting your workflows around it and I haven't solved that problem yet.

(That's if you don't want to go full Codex and have an agent play around with the PR. Personally I find that GPT-5.2 xhigh is incredibly good at analysing diffs-plus-context without tools.)

I recently started using LLMs to review my code before asking for a more formal review from colleagues. It's actually been surprisingly useful - why waste my colleagues time with small obvious things? But it's also gone much further than that sometimes with deeper reviews points. Even when I don't agree with them it's great having that little bit more food for thought - if anything it helps seed the review