Reviewing my posted code I should mention that the 'tool_choice' argument I'm passing is a default argument of the OpenAI client object. The code still breaks in the same way if I remove that argument from the function call. I think this is out of my hands to fix as it would require either a change to what instructor sends during the payload to DBX or how DBX interprets the payload. 

I did however find a workaround using LangChain's PydanticValidator. That seemed to work although it's not as direct of an implementation as instructor.