This label should apply to those who become institutionalized by the military. The long-term, or 'career' soldiers are generally those who have no direction in life and would otherwise FAIL in the REAL WORLD, so they join the military for a steady paycheck and/or structure/guidance in their lives, which the military provides through various courses, manuals, and mundane speeches, WHICH said ARMY TOOLS memorize bits and pieces of, for their own future speeches and spot corrections. Once these soldiers become NCO's, they generally do not have a clear understanding of their responsibilities nor how to act like DECENT human beings, so they revert to exerting their newly acquired power by less than decent means.
These soldiers can be found in administrative type jobs, where petty office politics prevail. The TOOL can be found driving his vehicle around post in search of lesser-ranking soldiers that they can 'correct' in proper wear of uniform, thus making the TOOL feel like he is "meeting the needs of the army and national defense". Another way to spot an ARMY TOOL is to listen for those who complain by 'legitimizing' their particular gripe by comparing it to an army regulation INFRACTION.
Friend 1: Why?
Homeschooler: Cus I'm F***in Homeschooled! Now I have no choice but to join the Army.
Freind 1: Dude life Sucks for Jake.
Freind 2: Why?
Freind 1: He can't get into college cus he's Homeschooled.
Freind 2: Damn that Sucks. What an Army Tool.