L5 longitude latitude source?

Hi, I looked around for the mechanism of the response for
chain.invoke({"input": "what is the weather in sf right now"})
is AIMessage(content='', additional_kwargs={'function_call': {'name': 'get_current_temperature', 'arguments': '{\n "latitude": 37.7749,\n "longitude": -122.4194\n}'}})
How come langchain got information about longitude and latitude of SF? It seems to me that the invoke method only select the best function get_current_temperature already, so where it get the parameter? Or it is returned by the LLM itself, not by any defined functions?