Using cmd.py to communicate with the Google A2A sample agent does not work.

[long0426]

I used a2a_samples/version_3_multi_agent/app/cmd to send a prompt to the google-a2a/samples/python/agents/helloworld agent, but it reported an error.

What do you want to send to the agent? (type ':q' or 'quit' to exit): hello world

📤 Sending JSON-RPC request:
{
  "jsonrpc": "2.0",
  "id": "b0e23093da17446f81bd599aefc5cd7b",
  "method": "tasks/send",
  "params": {
    "id": "924e6edbf4074716a6066fe69d43c7ce",
    "sessionId": "717d5f5178ea47ce89fb6f361934b427",
    "message": {
      "role": "user",
      "parts": [
        {
          "type": "text",
          "text": "hello world"
        }
      ]
    },
    "historyLength": null,
    "metadata": null
  }
}
Traceback (most recent call last):
  File "/root/project/python/a2a_samples/version_3_multi_agent/app/cmd/cmd.py", line 80, in cli
    task: Task = await client.send_task(payload)
                 ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
  File "/root/project/python/a2a_samples/version_3_multi_agent/client/client.py", line 80, in send_task
    return Task(**response["result"])  # ✅ Extract just the 'result' field
                  ~~~~~~~~^^^^^^^^^^
KeyError: 'result'

❌ Error while sending task: 'result'

[theailanguage]

Hi @long0426 thanks for the issue, this error can mean that the response from the agent does not have the key "result".

As per A2A spec, the JSON RPC Response must include a result on success. See
https://google-a2a.github.io/A2A/specification/#6112-jsonrpcresponse-object

Could you please print the Json response to see what response are you getting. Let me know. Not ruling out issues with the client, just want to see the response as the issue might be on the agent side!

Add something like before the return statement. Send me the print output please.

    # 🔍 Print the full raw response
    print("\n📥 Received JSON-RPC response:")
    print(json.dumps(response, indent=2))

Thanks
Kartik / the ai language

[long0426]

Hi @long0426 thanks for the issue, this error can mean that the response from the agent does not have the key "result".

As per A2A spec, the JSON RPC Response must include a result on success. See https://google-a2a.github.io/A2A/specification/#6112-jsonrpcresponse-object

Could you please print the Json response to see what response are you getting. Let me know. Not ruling out issues with the client, just want to see the response as the issue might be on the agent side!

Add something like before the return statement. Send me the print output please.

    # 🔍 Print the full raw response
    print("\n📥 Received JSON-RPC response:")
    print(json.dumps(response, indent=2))

Thanks Kartik / the ai language

📥 Received JSON-RPC response:
{
  "error": {
    "code": -32600,
    "data": [
      {
        "type": "literal_error",
        "loc": [
          "SendMessageRequest",
          "method"
        ],
        "msg": "Input should be 'message/send'",
        "input": "tasks/send",
        "ctx": {
          "expected": "'message/send'"
        },
        "url": "https://errors.pydantic.dev/2.11/v/literal_error"
      },
      {
        "type": "missing",
        "loc": [
          "SendMessageRequest",
          "params",
          "message",
          "messageId"
        ],
        "msg": "Field required",
        "input": {
          "role": "user",
          "parts": [
            {
              "type": "text",
              "text": "hi"
            }
          ]
        },
        "url": "https://errors.pydantic.dev/2.11/v/missing"
      },
      {
        "type": "literal_error",
        "loc": [
          "SendStreamingMessageRequest",
          "method"
        ],
        "msg": "Input should be 'message/stream'",
        "input": "tasks/send",
        "ctx": {
          "expected": "'message/stream'"
        },
        "url": "https://errors.pydantic.dev/2.11/v/literal_error"
      },
      {
        "type": "missing",
        "loc": [
          "SendStreamingMessageRequest",
          "params",
          "message",
          "messageId"
        ],
        "msg": "Field required",
        "input": {
          "role": "user",
          "parts": [
            {
              "type": "text",
              "text": "hi"
            }
          ]
        },
        "url": "https://errors.pydantic.dev/2.11/v/missing"
      },
      {
        "type": "literal_error",
        "loc": [
          "GetTaskRequest",
          "method"
        ],
        "msg": "Input should be 'tasks/get'",
        "input": "tasks/send",
        "ctx": {
          "expected": "'tasks/get'"
        },
        "url": "https://errors.pydantic.dev/2.11/v/literal_error"
      },
      {
        "type": "literal_error",
        "loc": [
          "CancelTaskRequest",
          "method"
        ],
        "msg": "Input should be 'tasks/cancel'",
        "input": "tasks/send",
        "ctx": {
          "expected": "'tasks/cancel'"
        },
        "url": "https://errors.pydantic.dev/2.11/v/literal_error"
      },
      {
        "type": "literal_error",
        "loc": [
          "SetTaskPushNotificationConfigRequest",
          "method"
        ],
        "msg": "Input should be 'tasks/pushNotificationConfig/set'",
        "input": "tasks/send",
        "ctx": {
          "expected": "'tasks/pushNotificationConfig/set'"
        },
        "url": "https://errors.pydantic.dev/2.11/v/literal_error"
      },
      {
        "type": "missing",
        "loc": [
          "SetTaskPushNotificationConfigRequest",
          "params",
          "pushNotificationConfig"
        ],
        "msg": "Field required",
        "input": {
          "id": "4417baf9614842e592eea0880316b0a5",
          "sessionId": "d30f5a3db9fa4f458e6227876e319808",
          "message": {
            "role": "user",
            "parts": [
              {
                "type": "text",
                "text": "hi"
              }
            ]
          },
          "historyLength": null,
          "metadata": null
        },
        "url": "https://errors.pydantic.dev/2.11/v/missing"
      },
      {
        "type": "missing",
        "loc": [
          "SetTaskPushNotificationConfigRequest",
          "params",
          "taskId"
        ],
        "msg": "Field required",
        "input": {
          "id": "4417baf9614842e592eea0880316b0a5",
          "sessionId": "d30f5a3db9fa4f458e6227876e319808",
          "message": {
            "role": "user",
            "parts": [
              {
                "type": "text",
                "text": "hi"
              }
            ]
          },
          "historyLength": null,
          "metadata": null
        },
        "url": "https://errors.pydantic.dev/2.11/v/missing"
      },
      {
        "type": "literal_error",
        "loc": [
          "GetTaskPushNotificationConfigRequest",
          "method"
        ],
        "msg": "Input should be 'tasks/pushNotificationConfig/get'",
        "input": "tasks/send",
        "ctx": {
          "expected": "'tasks/pushNotificationConfig/get'"
        },
        "url": "https://errors.pydantic.dev/2.11/v/literal_error"
      },
      {
        "type": "literal_error",
        "loc": [
          "TaskResubscriptionRequest",
          "method"
        ],
        "msg": "Input should be 'tasks/resubscribe'",
        "input": "tasks/send",
        "ctx": {
          "expected": "'tasks/resubscribe'"
        },
        "url": "https://errors.pydantic.dev/2.11/v/literal_error"
      }
    ],
    "message": "Request payload validation error"
  },
  "jsonrpc": "2.0"
}

[theailanguage]

Hi @long0426 I found the issue. A2A has ddeprecated tasks/send endpoint recently and shifted to message/send. So the client that you see in this repo uses the old spec hence the issue. Note that it is common for early stage software to deprecate existing specs and move to new ones and then the world follows. I'll update the client to use that.

In the mean time, you may use - https://github.com/theailanguage/a2a_samples/blob/main/version_5_a2a_sdk/client/client.py

This is the version 5 a2a sample that uses the python SDK. I'll message here when I have decided on and implemented a solution to this.

Thanks!
Kartik

[theailanguage]

a2aproject/A2A#578 - decprecation reference