Inputs for the custom function and for the endpoint

I successfully tested my custom function sendgrid_dynamic_send after barely a week on Xano.

Yet I feel something isn't right. I have about a dozen inputs for my function (all tested with the Run&Debug). Now at the endpoint level, I end up creating a few of those inputs again.

I've digged into this doc but that didn't aleviate my doubts:https://docs.xano.com/api/the-basics/custom#how-to-create-an-api-endpoint

Where can I read more (any relevant link in the forum)?

For example, am I correct in setting all the inputs needed for the personalizations array of objects inside the function only, and only a personalizations input at the endpoint level?