Has anyone else noticed that the tooltip attribute doesn’t function with a UnityEvent field? Or am I missing something obvious here?
There sadly does not appear to be any way of doing that.
Unity have stated that they don’t provide that functionality for ‘stability’ reasons (at least in older versions): Unity Issue Tracker - Custom Inspector Tooltips don't work with UnityEvent fields and no error is shown in script
It’s not quite the same, but you could maybe make use of HeaderAttributes for short tooltip-like comments.
Only solution, if you absolutely must have them, would be creating your own version of the UnityEvent class with all the functionality you’d need, but that’s probably a lot of work for little value.