Which description languague should I use for a webserver implemented using TidHttpServer?

Which description languague should I use for a webserver implemented using
TidHttpServer?

I am using Delphi XE2 Update 4 Indy 10
I have a webservice implemented with idHttpServer that answers to
traditional Http Get requests where I only interact with the variables
retrieved from the URI.
This webserver have many other funcions already built in for local area
network, etc. So I am considering to make it better than moving to a new
platform.
The number of concurrent acesses are very low: max of 5 per time. The
webservice retrieves data from a SQL server and answer with JSON.
I want to rewrite the services offering of this server in a such way that
can be described and retrieved. Pretty much like DCOM Iunknown and
Idispatch capabilities. I dont need it to be a public full implemented
language like WSDL.
For me the RESTful style for the architecture is closer of what I have
than anything related to SOAP.
I read a little that datasnap has an Indy core option and can do RESTful
however I do not want to use Apache or IIS, I want to be a regular Windows
application. I heard too many bad things about DataSnap...
I have read about AtomPub and RSDL, I dont know about others, but I need
that there is some code on delphi to start using it.
My question: which description language should I use that I can find
component/example to quickly start using it with my idHttpServer Server?