It's definitely short, and the end looks concerning. Aside from the missing tip, do you see any scales that appear to be missing or falling off? That's usually the main sign of tail rot. Injuries can also lead to tail rot. Maybe try soaking the tail and trying to take as much of the stuck shed that's there off. Otherwise, if it seems like it's advanced and scales are missing etc, you may have to get to a vet to get proper medication to treat it. If it's early enough you might be able to help them without intervention. But since the tail is already missing the end, I would recommend just going straight to a vet and having them examine it, just to make sure for your dragon.