.NET: Hosting with OpenAI Responses output yielding unexpected function call requests

The OpenAI Responses support is dutifully translating FunctionCallContent / FunctionResultContent from a hosted agent into function_call and function_call_output response items. But such content represents already-invoked functions, and function_call in Responses is actually a request from the server to invoke the corresponding function on the client. Commensurately, there's no situation where a server sends function_call_output, because that's intended for the client to send to the server. With how things are currently arranged, then, the hosted agent is sending notifications about functions it invoked but those will be interpreted by a responses client as a request for invocation.

To my knowledge, there's no general "this arbitrary function was invoked on the server" set of response items in the OpenAI Responses spec, so it's unclear what these should map to. It's possible the right answer for now is for the OpenAI Responses hosting to filter them out.

FunctionCallContent.InformationOnly conveys whether the FCC is information-only (e.g. a notification of a function already invoked) or whether it's a request for invocation.

cc: @ReubenBond, @DeagleGross, @westey-m, @rogerbarreto