How can I force Function calling then AgentFinish?

API
,
1

I implemented chatbot by referring to langchain.agents.agent.AgentExecutor like this,

prompt = ...
model = model.bind_tools([tool], tool_choice=tool_name)
parser = OpenAIToolsAgentOutputParser()
chain = prompt | model | parser

while self._should_continue(params):
    response = invoke_chain(...)
    if isinstance(response, AgentFinish):
        # final response
        ...
    else:
        # function calling invoked
        ...

model = model.bind_tools([tool], tool_choice=tool_name)

Here, this syntax(tool_choice) always invokes function calling, but I want to get final response(AgentFinish) after forcing function calling(OpenAIToolAgentAction).

Is there anything to do it?
If not, is it the best way to use separate models/chains(binded one and not binded one)?