API searchId documentation?

The API V3 swagger is filled with references coming back in the RESPONSE with searchId but doesnt say what it is. AI queries say its used for pagination, claims there is no official documentation, but is able to give me examples. I was able to use them by providing my own searchId and getting it back ... for SOME endpoints but NOT ALL.

But I'm wondering:

Is there an official page I'm not finding that explains how to use searchId ?

Does it really not work for some endpoints? I just get null back when I send it in my request to /device/devices but if I do /alert/alerts I get back the searchId I set in my query.

Thanks!