Using Function Tools on Managed Backend #185
Description
Hello,
Is there any way to use Function Tools with the managed backend solution?
I created a workflow in Agent Builder with several agents that use Function Tools, then deployed it on the managed backend. Deployment succeeds, but when an agent calls a function tool, execution gets stuck.
This is somewhat expected, since a function tool normally requires an external executor that receives the function call, runs it with the given parameters, and returns the output back to the agent. However, the fact that Agent Builder allows adding Function Tools to agents and still allows deployment to the OpenAI-managed backend made me think I might be missing something.
My assumption is that, on the managed backend, OpenAI also translates the workflow into something similar to Agents SDK code and runs it server-side, much like the AgentBuilder utility does when it generates the SDK translation for us. Of course, it would not be exactly the same: the code generated by Agent Builder leaves function outputs as unimplemented functions, which would at least lead to a function call trace with no real output, whereas on the OpenAI-managed backend I do not even see a function call span being created. Instead, execution appears to stop right after the model emits the function call.
Given that behavior, it makes sense that the run cannot continue, because there is no visible mechanism to execute the function and feed the result back into the workflow.
So my question is: are Function Tools actually supported in the managed backend setup? If yes, how are they supposed to be executed? If not, would it make sense either to prevent deploying workflows that depend on them, or at least to show a warning?