The client knows nothing about the API end points associated with this data, except via URLs and hypermedia controls (links and forms) discoverable within the HTML itself. If the state of the resource changes such that the allowable actions available on that resource change (for example, if the account goes into overdraft) then the HTML response would change to show the new set of actions available. If the client kno…
That said, the situation isn't entirely dire. With some standard linking conventions (e.g RFC 8288 [1]), you can largely make an API that is pleasant to interact with in code as well. That the links/actions are enumerated is good for humans to learn how to manipulate the resource. That they have persistent rels is good for telling a computer how to do the same.
Think as an example. A human reading the HTML source will see that there's a related stylesheet available at "foo". But a program wanting to render HTML will check for the existence of links with rel="stylesheet".
1: https://datatracker.ietf.org/doc/html/rfc8288#section-2.1.2