Hey! I’m just about to make a PR, and I realized now that I might not have understood you completely here. Did you mean “annotate with AutoTokenizer, and let the documentation take care of all the other details”?
Currently, the PR annotates as follows
class AutoTokenizer:
    @classmethod
    def from_pretrained(<the arguments>) -> "PreTrainedTokenizer":
         ...

since all instances returned by the method are indeed instances of subclasses of PreTrainedTokenizer. Let me know if you think AutoTokenizer would be better, and I’ll change my PR.