How does it explain what the request and response formats / fields are?
(1) - That detail is covered by API specs like Swagger (2) - Two endpoints that return the same resource (of the back of two different operations on the same resource) may return a slightly different format/field. This is up to the developer of the API and best captured in API spces.
(For that matter, if you output the diagram in a format that supports hyperlinks like SVG or PDF, you could link from the diagram directly into Swagger.)
You brought another very good point about being able to hyperlink directly into Swagger, something we have been talking about a lot recently. Unfortunately, we have not come across a tool that does this satisfactorily.