So, my Steam needed a manual re-install because of some glitch that had it close automatically as soon as it finished loading. I backed up all my games and returned them to the default steam games folder and didn't detect them automatically.

For most games, just clicking to install them made steam notice they were there, and have them appear on my games list. The big issue here is GTA V.

GTA V is a 60 gig game, and re-installing that from scratch is NOT an option on my connection. I also have a very small hard drive, so when I go to "install" the game to make Steam realize that it's actually in the folder, it tells me I don't have enough hard disk space (despite the game being fully installed).

Is there a way to have steam do a quick scan of the default games folder just to see whats in it without me having to clear up 20 gigs of space Steam thinks it needs?