Dare Obasanjo disagrees with Steve Vinoski and Ryan Tomayko and makes the case for a REST description language:
The examples of Atom service documents and link elements in HTML, highlight that there is real world value in describing the interfaces to your RESTful Web Service. In addition, Atom service documents show that you can define an interface definition language for Web services without resorting to reinventing CORBA IDL (i.e. WSDL). So I respectfully disagree with Ryan Tomayko…just because my life is made easier with a service description language doesn’t make WSDL a good idea.
I’m not at all opposed to what Dare is suggesting — but I claim that an Atom service documents and link constructions in HTML GET forms is so wildly different from WSDL, IDL and other description formats for specialized interfaces that calling all of them “a description language” confuses the issue.
REST relies on hypermedia. An Atom service document does, too — WSDL and IDL don’t.