Actually, looking at this again, the phrasing on the documentation for the tag and version is a little odd. The use of "should" and "only supported" suggests that they are meant to be filled by the user, when in fact they're currently only output parameters. I'm not sure what's better phrasing for this, though.
I've slightly adjusted this in v3. Note that I've also adjusted some of the types and included a basic test. Provided we can all live with the API as it currently is, I'd suggest to merge it this way. I'd really like to have this in 1.7, but I'm not going to hold off on starting the 1.7 release process much longer. We'll still have quite some time to make documentation changes, of course.