[phatfish]

With GPT5 there is a persona (I think, I forget what the call it) setting, I chose "Robot" and that shut it up pretty well.

[jgruber]

Same. The GPT5 “Robot” persona does what no custom “be terse”, “no fluff”, etc. custom prompt ever could. It actually makes ChatGPT terse and to-the-point and eliminates (or at least greatly reduces) fluff. I love it.