I haven't had much trouble with GPT 3.5 or 4 function calls returning in an undesirable format recently. I did get a few bad syntax responses when OpenAI first rolled it out, but not for the past few months.
Llama 2 can also pick the function call format up, given sufficient training data that contains function call responses, though you'll then have to parse the returned object out of the text-based response.
Llama 2 can also pick the function call format up, given sufficient training data that contains function call responses, though you'll then have to parse the returned object out of the text-based response.