I'd like to see what kind of limitations could be introduced on mental magic. Distance, or passage of time dimming the impressions, or a question of reliability (maybe retrocognition is as hard to trust as precognition, for whatever reason), or sheer difficulty to translate (despite having used it myself, I don't think someone with telemetry could actually get perfect impressions of other humans from objects; how objects "perceive" humans is obviously going to be different from how humans do). But too often, just as with the god who has to be omniscient or powerless, the assumption seems to be that mental magic is perfectly clear or perfectly wayward.
I'd like to see what kind of limitations could be introduced on mental magic.
Maybe the mage feels whatever emotions the people around him feel. So, if the mage is talking to a friend, and an angry person walks by, the mage gets angry at his friend. It would cause the mage to have mood swings, which would drive away people. So, that mage would have a pretty bad social life.
Apologies for coming along years late, but here's the limitations I use for telepathy when it comes to gathering evidence and such: the telepath can only see what the victim is able to remember. Memories aren't usually very high fidelity, and they tend to focus on a few objects, so a witness to a murder may only be able to remember that the murderer was wearing a red shirt and was tall. They work wonders as lie detectors, with the caveat that they can only detect conscious lies (if a person has managed to completely convince (him/her)self of an alternate version of what really happened, then that's what a telepath will see as truth.