Avoid second roundtrip when call functions

[Grogdunn]

Expected Behavior
For some customers we do not have necessity to pass the function-result to LLMs again.

Eg: extract some information from a blob of text and save it in structured mode. That can be accomplished with a function call with in input the "data structure" but the output is not necessary, so we can avoid totally the "second call" to LLM.

Current Behavior
Every function must return a value that is passed to LLM to produce a nice output.

Context
As workaround we implement some function with "spying" capability (like tests) and use it to grab the "first call" data. And ignore completly the second call-result.

We try to add this feature in spring-ai I think that can be useful to others. Or at least anyone can decide.

[tzolov]

@Grogdunn , are you referring to providing support for Function<SomeRequest, Void>? E.g. function with Void response?
If so shouldn't the implementation detect the Void response definition and handle it accordingly? rather than masking it via fake string response and additional property flags?

[Grogdunn]

Ok! Good point

[Grogdunn]

@tzolov Ok Done, if you use a Function<Input, Void> or a Consumer the second round-trip is skipped

EDIT:
if more function are called (if model support it) even if only one called function returns a value the second roundtrip is done.