There are parrotfish, and there are parrotfish ...
Yours is a Quoy's parrotfish, Scarus quoyi - and a real beauty, at that! In my experience, as well as in my reading on these guys, Quoy's are the most reef-safe of all parrots. They feed on various algaes, and are pretty careful about avoiding corals. They will scrape your liverock pretty clean though, and may - just as their larger cousins do - poop sugar-fine white sand. They're also among the smallest of parrotfish, and rarely - if ever - reach a foot long (30cm) in our aquariums.
~Bruce, with a Quoy's parrotfish in quarantine