To add to what Mo posted... the thing you are looking for is often called Service Mapping Description, or at least that would feed into something that generated the docs.
Tooling around this doesn't get enough attention (my present-but-hind-sighted view), and is probably one of the things that has held back json-rpc compared to other specifications.
But it is easy enough to use json-schema to describe it, in much the same way RAML also uses json-schema.
No idea how widely used dojo is these days, but...