Like suppose you issue a command to Opus or Fable which doesn't make sense and requires a lot of work. It will almost certainly not push back on your silly request and go ahead and burn as many tokens as it can doing the wrong task. This happens to me all the time.
Or if I was to tell a model to do something and it realized it could only do it by hacking into another service, by all means it should ask me if I want it to hack and not go ahead and do it by itself.