Awareness

Awareness is a perk in Fallout, Fallout 2, and Fallout Tactics: Brotherhood of Steel.

You are more likely to notice details about people. Awareness will give more detailed information about them when you perform an Examine. The perk tells you the target's hitpoints, its weapon and ammunition count. It does not indicate which limbs, if any, are crippled.

Fallout 3
In Fallout 3, both health and equipped weapon are visible in V.A.T.S - although health is merely a percentage, the damage from a successful shot gives a rough scale. However, NPCs will never run out of ammunition (with the exception of companions using weapons given to them) and it is impossible to determine how much ammunition is in a weapon without manually counting although this is far less important since combat isn't turn-based. On the other hand, V.A.T.S. does indicate limb damage.