The REST API is documented in a swagger.json file. This file is meant to be consumed by a computer, but you can use the Swagger Editor to obtain a human-friendly view.
Incomplete swagger.json
The swagger.json file does not distinguish between synchronous and asynchronous endpoints.
If a request is made to an asynchronous endpoint, then the response will have status code 202 (Accepted).
The Location
header in the response contains the URL that can be polled for the result.