There should be several APIs, one for each domain (DOM, Debugging, Network, Storage, etc.) in the remote debugging protocol.
+1 on splitting the APIs on a not-quite-related tangent, the FireBug folks are also working on a Remote Debug API, but haven't gotten much further than "Scripts" and "Console" -level APIs. See: http://getfirebug.com/wiki/index.php/Crossfire_Protocol_Reference CrossFire is also currently only spec'd in HTML. If there were ever any interest in "standardizing" these sorts of APIs, doing it in WebIDL makes the most sense (to me, today). Basically, I think Web Inspector is a bit ahead of FireBug here. Is there any desire to pull in the FireBug guys to standardize on these APIs?
Am aggressively triaging the bugs. Not sure we need this one filed. Sounds like inspector.idl serves us fine for now. We'll split it later under some refactoring bugs.