It's hard to see how the different 3pid management APIs interact with each other at a glance

The endpoints should be descriptive in the table of contents

Locate the Matrix specification's table of contents and the section covering the different 3pid management APIs. Review how those endpoints are currently described, then update the table of contents so the endpoints and their relationships are descriptive at a glance; the work is done when the API interactions are easier to distinguish there.

Written by the indexing model from the issue text.