When we say all RESTful representations must be self-descriptive, we mean to say that any client who makes a valid request of the underlying resource will always receive the information it needs to understand the representation, including what actions it can take next. If your resource doesn’t allow for the possibility that a human being might perform a GET, you’re missing the boat on REST.

Read the entire post at http://blog.devx.com/2012/08/truly-restful-apis-the-human-r.html