You can look at this post here for some ideas then for calling functions with AI-gathered data:
The “weather” demonstration of functions in API shows a field that must be filled by the AI, particularly of the choice Celsius/Fahrenheit, and another “location” (that doesn’t state explicitly-enough what is allowed). You can state that all parameters are mandatory and must be user-provided data in the function description to ensure they are filled and not hallucinated on.
I’m not seeing particularly the use-case or optimum solution where someone needs to be chatting with an AI, and then it decides on its own it can send a mail-merge email via function. Providing it a list of all the forms, or a function to get the forms list, or then pass how the requested one works as a new function API call, details of when to use them and its job of being a template assistant is a lot of prompt and chain to follow, where putting the right data into a function call is not the biggest problem.