Hi there! The argument is_pretokenized is for when your inputs have been pre-tokenized, that is, split into words (since the tokenizers of transformers are all subwords tokenizers). So you should pass your tokenizer ["I", "am", "talking", "about", "Kavanaugh"] with is_pretokenized=True for instance, not ["I", "am", "talk", "##ing", "about", "Ka", "##vana", "##ugh"].
If you just want to add the special tokens, the method you want to call is tokenizer.prepare_for_model I believe.
I could make something clearer in the docs but you’re far from being the first user that got confused, so I think we are going to rename this argument to something less confusing.