No, it actually does both - which is why I was so interested in it initially.
from the above link: "generates code to be used to easily build RPC clients and servers"
TBF, I haven't used it as a developer, but I did contract work with a company that had invested in it heavily. From what I saw of their workflow, it ended up being a pretty nice bootstrap tool and little more.
edit: Oh, I see what you're saying. Yes, you're correct - thrift does not wrap existing APIs.