Hi,
I think RPC URL should be added to rpc-spec.txt, perhaps even RPC wiki page.
I read the rpc-spec.txt and tried to POST requests to http://host:port/ but I got a "405: Method Not Allowed". I found in the forums that the correct URL to use is http://host:port/transmission/rpc but it really should be mentioned where API it self is documented.
In section 3.3, where it says "Say we want to get the name and total size of torrents #7 and #10.", ids parameter should be added to the request to match that text and response shown.
Thanks