This isn’t an answer to your question, but my understanding of the matter:
As far as I know OpenAI, what they would want to tell you is this:
“don’t worry about it.”
In like a NY italian drawl kinda way.
OAI likes its black boxes, and trying to figure them out can get your account flagged.
(discussion about o1 Your prompt was flagged as potentially violating our usage policy)
My personal suggestion - if you want maximal control - would be to ditch tools/function calls altogether and roll you own schema.
OAI pricing is completely divorced from cost anyways, if they really cared about that then we’d know by now…