Yes, you are going to be charged unseen and unknown amounts. OpenAI went out of their way to return no token usage and no report of the internal language used calling functions, and then combined that with a new usage page that removes the prior by-the-minute token usage.
You write an “instruction” to guide the AI. Is that wrapped in hundreds of tokens telling the AI what it can and cannot do with a “user” instruction provided there, like custom instructions in ChatGPT?
You upload a file. Does that come with 500 tokens of instruction and functions telling the AI to recursively browse little chunks of the file? (answer: yes it does, a myfiles_browser function that is not documented as an expense that is allowed to operate recursively “browsing” your uploaded files.)
You enable code interpreter. More unseen system instructions telling it how to act and how to call and output. Throw in a few more instructions to iterate until it’s sure?
And then it calls one of those functions you didn’t program yourself, and it continues to loop because of a faulty context system that doesn’t let the AI fix its errors…while having threads loaded up to the maximum of the model’s context, retrieval loaded up to the maximum of the model’s context (which is exactly what is described in the documentation).
All that making a “test, are you there” message potentially approach $1.
Until OpenAI addresses multiple issues, all which are at the developer’s expense, I would avoid this system, and look at developing your own RAG solution for “answer about my documents”.