At least in American slang "a tool" is synonymous with someone who is rude, uncaring, and generally arrogant. A "massive tool" is someone who takes all of those properties up a level.

"Tool" is a synonym for "dick" that you can utter even in polite company.

A "tool" in this context is something to be avoided :

http://www.urbandictionary.com/define.php?term=tool

http://en.wiktionary.org/wiki/tool#Noun I guess it's #7: An obnoxious or uptight person.

in this context a "tool" is a synonym for "dick"... basically stating that Microsoft are a bunch of dicks.

Excerpted from Urban Dictionary: "The tool is usually someone who is unwelcome but no one has the balls to tell them to get lost. The tool is alwasys making comments that are out-of-place, out-of-line or just plain stupid. The tool is always trying too hard to fit in, and because of this, never will."