1) The OpenAI API will be queried each time a "prompt-function" is called in python code. If you provide the `functions` argument in order to use function-calling then magentic will not execute the function the LLM has chosen, instead it returns a `FunctionCall` instance which you can validate before calling.

2) I haven't measured additional latency but it should be negligible in comparison to the speed of generation of the LLM. And since it makes it easy to use streaming and async functions you might be able to achieve much faster generation speeds overall - see the Async section in the README. Token usage should also be a negligible change from calling the OpenAI API directly - the only "prompting" magentic does currently is in naming the functions sent to OpenAI, all other input tokens are written by the user. A user switching from explicitly defining the output schema in the prompt to using function-calling via magentic might actually save a few tokens.

3) Functionality is not deterministic, even with `temperature=0`, but since we're working with python functions one option is to just add the `@cache` decorator. This would save you tokens and time when calling the same prompt-function with the same inputs.

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1) https://github.com/jackmpcollins/magentic#usage 2) https://github.com/jackmpcollins/magentic#asyncio 3) https://docs.python.org/3/library/functools.html#functools.c...