I remember Clippy, but I don't remember why it was annoying. I am thinking that Robert Brooke's 3 laws of robotics applies here. (He had written one for AI but I think his thoughts on robotics are more relavent to AI agents).
I think it was the modal dialog box that forced you to stop what you were doing and click 'piss off clippy', rather than being able to ignore it.
Additionally, there was an option that was on by default to use Clippy in place of confirmation dialogs. You'd try to close an unsaved file and instead of the usual Windows dialog you'd get Clippy asking whether you'd like to save changes instead.
So going by https://rodneybrooks.com/rodney-brooks-three-laws-of-robotic...
That would be violating the second design principle:
"When robots and people coexist in the same spaces, the robots must not take away from people’s agency, particularly when the robots are failing, as inevitably they will at times."
With a physical robot, if it fails and freezes, it turns into a hazard.
With Clippy, it intrusively stops humans from being able to do what they are doing.
It tends to randomly barge into your UI when you thought you dismissed/disabled it. And never provides any useful information or suggestions.
"It looks like you’re trying to write a term paper at 2am the night before it’s due, do you want me to just put out some LLM slop and hope for the best?"