Wiktionary
tell all
vb. 1 (context idiomatic English) To reveal everything, particularly information that is normally withheld. 2 (&lit tell all English)
Usage examples of "tell all".
I wanted to ask them how they could tell all this from the tilt of a hansom cab, but the answer would only make me feel a fool for not being able to tell myself.
You know her spirit: if we would not set her free, she would tell all when we landed.
He would cook mesoup with fish scales in it as a remedy, and then tell all of myfavorite reed girls what I looked like with green skin.
Dain Waris, reclining on his elbow, bade him speak and tell all the news.