[BUG] A2A Doesn't Work on 1.2.0 #572
Description
Checks
- I have updated to the lastest minor and patch version of Strands
- I have checked the documentation and this is not expected behavior
- I have searched ./issues and there are no duplicates of my issue
Strands Version
1.2.0
Python Version
3.12.7
Operating System
mac0S 15.5
Installation Method
pip
Steps to Reproduce
Run this example server
import logging
from strands_tools.calculator import calculator
from strands import Agent
from strands.multiagent.a2a import A2AServer
logging.basicConfig(level=logging.INFO)
# Create a Strands agent
strands_agent = Agent(
name="Calculator Agent",
description="A calculator agent that can perform basic arithmetic operations.",
tools=[calculator],
callback_handler=None
)
# Create A2A server (streaming enabled by default)
a2a_server = A2AServer(agent=strands_agent)
# Start the server
a2a_server.serve()
Expected Behavior
❯ python 4_a2a_server.py
INFO: Started server process [92853]
INFO: Waiting for application startup.
INFO: Application startup complete.
INFO: Uvicorn running on http://0.0.0.0:9000 (Press CTRL+C to quit)
^CINFO: Shutting down
INFO: Waiting for application shutdown.
INFO: Application shutdown complete.
INFO: Finished server process [92853]
This works on Strands 1.1.0
Actual Behavior
❯ python 4_a2a_server.py
Strands A2A server encountered exception.
Traceback (most recent call last):
File "/Users/mi-onda/.pyenv/versions/3.12.7/lib/python3.12/site-packages/strands/multiagent/a2a/server.py", line 228, in serve
uvicorn.run(self.to_starlette_app(), host=host or self.host, port=port or self.port, **kwargs)
^^^^^^^^^^^^^^^^^^^^^^^
File "/Users/mi-onda/.pyenv/versions/3.12.7/lib/python3.12/site-packages/strands/multiagent/a2a/server.py", line 171, in to_starlette_app
a2a_app = A2AStarletteApplication(agent_card=self.public_agent_card, http_handler=self.request_handler).build()
^^^^^^^^^^^^^^^^^^^^^^
File "/Users/mi-onda/.pyenv/versions/3.12.7/lib/python3.12/site-packages/strands/multiagent/a2a/server.py", line 123, in public_agent_card
return AgentCard(
^^^^^^^^^^
File "/Users/mi-onda/.pyenv/versions/3.12.7/lib/python3.12/site-packages/pydantic/main.py", line 253, in __init__
validated_self = self.__pydantic_validator__.validate_python(data, self_instance=self)
^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
pydantic_core._pydantic_core.ValidationError: 2 validation errors for AgentCard
defaultInputModes
Field required [type=missing, input_value={'name': '俳句エージ...y=None, streaming=True)}, input_type=dict]
For further information visit https://errors.pydantic.dev/2.11/v/missing
defaultOutputModes
Field required [type=missing, input_value={'name': '俳句エージ...y=None, streaming=True)}, input_type=dict]
For further information visit https://errors.pydantic.dev/2.11/v/missing
Additional Context
a2a-protocol 0.1.0
a2a-sdk 0.2.16
python-a2a 0.5.9
Possible Solution
No response
Related Issues
No response