使用python-a2a包调用本地A2A计算器Agent时通信失败问题求助

大家好，我最近在用python-a2a包开发一个Agent-to-Agent的计算器示例，但不管怎么调整请求URL，都没法和本地运行的Agent服务建立通信，一直返回错误。我不确定是不是包版本不兼容的问题，想请大家帮忙看看哪里出了问题。

报错日志 #

我先尝试将客户端URL设为http://127.0.0.1:5001/a2a，得到如下报错：

A2ACalcClient initialized for URL: http://127.0.0.1:5001/a2a
Sending calculation request: add(a=5, b=3)
Unexpected response type from A2A agent: error
Full response content: ErrorContent(message='Failed to communicate with agent at http://127.0.0.1:5001/a2a/a2a. Tried multiple endpoint variations.', type=<ContentType.ERROR: 'error'>)

后来又把URL简化为http://127.0.0.1:5001，还是收到类似的通信失败错误：

A2ACalcClient initialized for URL: http://127.0.0.1:5001
Sending calculation request: add(a=5, b=3)
Unexpected response type from A2A agent: error
Full response content: ErrorContent(message='Failed to communicate with agent at http://127.0.0.1:5001/tasks/send. Tried multiple endpoint variations.', type=<ContentType.ERROR: 'error'>)

服务端代码 #

我编写的Calculator Agent服务端代码如下：

import math
from python_a2a import (
    A2AServer,
    Message,
    TextContent,
    FunctionCallContent,
    FunctionResponseContent,
    FunctionParameter,
    MessageRole,
    run_server,
    Task
)

class CalculatorAgent(A2AServer):
    def handle_message(self, message):
        if message.content.type == "text":
            return Message(
                content=TextContent(
                    text="I'm a Python A2A calculator agent. You can call my functions:\n"
                    "- calculate: Basic arithmetic (operation, a, b)\n"
                    "- sqrt: Square root (value)"
                ),
                role=MessageRole.AGENT,
                parent_message_id=message.message_id,
                conversation_id=message.conversation_id
            )
        elif message.content.type == "function_call":
            function_name = message.content.name
            params = {p.name: p.value for p in message.content.parameters}
            try:
                if function_name == "calculate":
                    operation = params.get("operation", "add")
                    a = float(params.get("a", 0))
                    b = float(params.get("b", 0))
                    if operation == "add":
                        result = a + b
                    elif operation == "subtract":
                        result = a - b
                    elif operation == "multiply":
                        result = a * b
                    elif operation == "divide":
                        if b == 0:
                            raise ValueError("Cannot divide by zero")
                        result = a / b
                    else:
                        raise ValueError(f"Unknown operation: {operation}")
                    return Message(
                        content=FunctionResponseContent(
                            name="calculate",
                            response={"result": result}
                        ),
                        role=MessageRole.AGENT,
                        parent_message_id=message.message_id,
                        conversation_id=message.conversation_id
                    )
                elif function_name == "sqrt":
                    value = float(params.get("value", 0))
                    if value < 0:
                        raise ValueError("Cannot calculate square root of negative number")
                    result = math.sqrt(value)
                    return Message(
                        content=FunctionResponseContent(
                            name="sqrt",
                            response={"result": result}
                        ),
                        role=MessageRole.AGENT,
                        parent_message_id=message.message_id,
                        conversation_id=message.conversation_id
                    )
            except Exception as e:
                return Message(
                    content=FunctionResponseContent(
                        name=function_name,
                        response={"error": str(e)}
                    ),
                    role=MessageRole.AGENT,
                    parent_message_id=message.message_id,
                    conversation_id=message.conversation_id
                )

if __name__ == "__main__":
    agent = CalculatorAgent()
    run_server(agent, host="0.0.0.0", port=5001)

客户端代码 #

对应的客户端调用代码：

import python_a2a
from python_a2a import (
    A2AClient,
    Message,
    FunctionCallContent,
    FunctionParameter,
    MessageRole
)

class A2ACalcClient:
    """
    A class to encapsulate the communication with a Python A2A agent.
    """
    def __init__(self, a2a_url: str):
        """
        Initializes the A2ACalcClient with the A2A agent's URL.

        Args:
            a2a_url: The URL of the Python A2A agent (e.g., "http://127.0.0.1:5001").
        """
        self.client = A2AClient(a2a_url)
        print(f"A2ACalcClient initialized for URL: {a2a_url}")

    def send_calculation_request(self, operation: str, a: int, b: int) -> int | None:
        """
        Sends a function call message to the A2A agent to perform a calculation.

        Args:
            operation: The mathematical operation (e.g., "add", "subtract", "multiply", "divide").
            a: The first operand.
            b: The second operand.

        Returns:
            The result of the calculation if successful, otherwise None.
        """
        print(f"Sending calculation request: {operation}(a={a}, b={b})")
        function_call_content = FunctionCallContent(
            name="calculate",
            parameters=[
                FunctionParameter(name="operation", value=operation),
                FunctionParameter(name="a", value=a),
                FunctionParameter(name="b", value=b)
            ]
        )
        function_call_message = Message(
            content=function_call_content,
            role=MessageRole.USER
        )
        try:
            response = self.client.send_message(function_call_message)
            if response.content.type == "function_response":
                result = response.content.response.get("result")
                if result is not None:
                    print(f"Received result from A2A agent: {result}")
                    return result
                else:
                    print("Function response received, but 'result' key is missing in the response.")
            else:
                print(f"Unexpected response type from A2A agent: {response.content.type}")
                print(f"Full response content: {response.content}")
        except Exception as e:
            print(f"Error sending calculation request: {str(e)}")
        return None

# 调用示例
# client = A2ACalcClient("http://127.0.0.1:5001")
# client.send_calculation_request("add", 5, 3)

我已经确认服务端正常启动，端口5001也没有被其他程序占用，但客户端始终无法正确命中服务端的处理接口。有没有用过这个包的朋友能指点下，是我URL路径写错了，还是服务端的实现有问题？

内容来源于stack exchange