I think it’s best to view this separately. Langchain provides its own agent type (next to the commonly used ReAct agent) to interact with OpenAI functions. Lemon AI functions are standalone fallback mechanisms that will be used by the model in specific situations where near-deterministic model behavior is especially important, a bit similar to the functions offered by OpenAI just suitable for open source models. You can combine Lemon functions with any Langchain agent type. Hope this helps!