Person 1:did you hear Hillary Clinton during the debates?
Person 2: yeah, what a tool! We need someone who's hip enough to bring Twitter to the oval office!
A guy who wears sleeveless shirts, and lets his tits hang out on the sides. He wears Everlast shorts and is proud of his road rash. A true Somervillian douchebag.
Let's keep it simple. "Tool" is simply a re-Anglicization of the Yiddish slang "Putz" which means the same as the original American slang term "Dick" in both its direct literal and anatomical meanings and its indirect figurative ones. Any context where "Tool" works, the term "Putz" or "Dick" could be substituted. But if you did that, people would know you're a total tool.
Often refered to someone who is a weapon of mass destruction for the female genitalia. Someome who will "reach bottom" and "stretch out the edges". Someome whos talent is unrivaled by anyone else in the company he works for. Someone who is truley undervalued for the work hes capable of accomplishing.