This is actually a combination of issues. On each of the following pages:

• https://musicbrainz.org/user/naught101/ratings and https://musicbrainz.org/user/naught101/ratings/<artist>
• https://musicbrainz.org/user/naught101/tag/<tag>
• https://musicbrainz.org/collection/<collection_id>

I would like to be able to add

• Ratings
• Tags
• Collections (add item to collection)

For any listed item.

This would be a good way to make sure that everything I'm interested in is well tagged and rated, and would make collection management heaps easier.