Someone who is more than simply a tool. So much of a tool in fact, that since there is not a more tool-ish word than tool, they can only be described as a "tool bag," logically. One who has the tool quality of so many tools, that a mechanic's collection of tools does not contain as many tools as would equal the level of tooldom that a "tool bag" contains. Therefore, their tool level is higher than tool and moves up to "tool bag."
A group of sophmores is a bunch a tools ::AS TO:: A single freshman is a tool bag.
Good Charlotte are tools ::AS TO:: Ryan Seacrest is a tool bag.