The simple truth is, he shouldn't be on Twitter. He just shouldn't. I understand there are people who love him "poking the left in the eye", but his ass should not be on Twitter. And he absolutely has diarrhea of the mouth. He talks too much, brags too much, and deflects too much. His biggest problem as President is he opens his mouth. If he'd just shut up and let his actions do the speaking, he wouldn't be such a bad POTUS, but his obnoxious arrogance won't let him keep quiet. I agree with you that his actions are what really matter, and on that front, he's not done bad, but he is his own worst enemy by constantly running off at the mouth and giving his critics something to attack.
All of that said, actions should speak louder than words. His actions are not near the level of incompetence his detractors would like to paint them as. He just needs to cut down on the talking.