Function Calling Work but Return an Empty Content String (Use Qwen2.5-32B-Instruct (support function calling))

[aqachun]

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Example Code

from langchain_openai import ChatOpenAI
from langchain_core.tools import tool
import os

llm = ChatOpenAI(
    model="qwen2.5-32b-instruct",
    api_key=os.getenv("BAILIAN_API_KEY"),
    base_url=os.getenv("BAILIAN_BASE_URL")
)


@tool
def multiply(a: int, b: int) -> int:
    """Multiply a and b

    Args:
        a (int): first int
        b (int): second int
    """

    return a * b

llm_with_tools = llm.bind_tools([multiply])

result = llm_with_tools.invoke("What is 2 multiplied by 3?")
print(result)

Description

• I'm working on completing the LangChain tutorial about extraction. I used the code above to implement function calling, leveraging the Aliyun Bailian API (OpenAI compatible). I've confirmed that the model (qwen2.5-32b-instruct) supports function calling. However, when I run the code, I receive an empty content string, even though the function calling itself works properly:

• output:

content='' additional_kwargs={'tool_calls': [{'id': 'call_010ae4cd0e0645aaab68f3', 'function': {'arguments': '{"a": 2, "b": 3}', 'name': 'multiply'}, 'type': 'function', 'index': 0}], 'refusal': None} response_metadata={'token_usage': {'completion_tokens': 22, 'prompt_tokens': 194, 'total_tokens': 216, 'completion_tokens_details': None, 'prompt_tokens_details': None}, 'model_name': 'qwen2.5-32b-instruct', 'system_fingerprint': None, 'finish_reason': 'tool_calls', 'logprobs': None} id='run-8e018e81-f711-45c8-b989-2b7d7b43086c-0' tool_calls=[{'name': 'multiply', 'args': {'a': 2, 'b': 3}, 'id': 'call_010ae4cd0e0645aaab68f3', 'type': 'tool_call'}] usage_metadata={'input_tokens': 194, 'output_tokens': 22, 'total_tokens': 216, 'input_token_details': {}, 'output_token_details': {}}

System Info

plangchain==0.3.19
langchain-core==0.3.40
langchain-openai==0.3.2
langchain-text-splitters==0.3.6

M1 Arm Mac platform

Python 3.12.8