If I recall correctly Tattletale’s power basically lets her put information together from any amount of hints - stuff like analysing Skitter on their first meeting just from her (re)actions or cracking a code without the work you usually have to put in it, guessing your password just from the stuff you decorate your workplace with or making a educated guess about endbringers. Even better/worse her power fills the holes for her so once she gets going it provides her with more and more information- within limits obviously. Using it too long or trying to get too much information out of nothing gives her a migraine.
But I'm absolutely certain that she can't read minds - the only telepath in the Worm-verse is still the Smurf.