Get HS descriptors through control port

I'm interested in writing a program that given an onion address, it displays information about the Hidden Service. For example, the current introduction points, the long-term public key, the current responsible HSDirs, whether it uses a descriptor cookie, etc. It will be both helpful for debugging HSes and for understanding how they work.

One of the first steps for the creation of such a program is having a nice way of exposing the HS descriptors using the control port. A command like GETINFO dir/rendezvous/<onion> could do the trick.

Do you find this useful? Would you merge it into mainline Tor?