I need a single word in English encompassing a specific quality of someone who is so aware and astute that can easily understand and judge other people and their intentions prior to any attempt by them. Such people usually so experienced and sharp that can judge people often properly and make best decisions at the due time.
Harry: do you remember that wheeler-dealer who was in the office about two months ago Jason?
Jason: who exactly?
Harry: the agent who came here to get into partnership with our company's main stockholders!
Jason: ah, the bastard who was trying to play dirty against our holding by informing our rivals about our latest products and their qualities.
Harry: bingo, you hit the mark.
Jason: I'll always remember how Dr. Smith by exchanging a couple of sentences with him at the first meeting, noticed his under the belt intent and the way he gave the guy that runaround.
Harry: haha, yea. Doctor is a really ........... man.
I wonder what do you call Dr. Smith in this scenario.
The only word that comes to my mind is "shrewd", but I'm not sure if it is exactly what I need.