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feat(a2a): add A2AAgent class as an implementation of the agent interface for remote A2A protocol based agents #1174

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feat(a2a): add A2AAgent class as an implementation of the agent interface for remote A2A protocol based agents #1174

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@awsarron awsarron commented Nov 13, 2025 •
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Description

Adds an A2AAgent class that makes it simple to consume remote A2A agents and invoke them like any other Strands Agents.

Implements the Protocol in #1126.

Example usage:

from strands import Agent, tool
from strands.agent.a2a_agent import A2AAgent

# Create an A2AAgent to connect to a remote A2A server
a2a_agent = A2AAgent(endpoint="http://localhost:9000")

# Expose the A2AAgent as a tool for our Strands agent to consume
@tool(name="calculator")
def a2a_agent_tool(prompt: str) -> str:
    """Invoke an agent that performs calculations"""
    return str(a2a_agent(prompt))

# Connect the second agent to our A2A agent
agent = Agent(tools=[a2a_agent_tool])

# Invoke the second agent
agent("Show me 10 ^ 6")

print(agent.messages)

Output:

I'll calculate 10^6 for you.
Tool #1: calculator
10^6 = 1,000,000

This represents 10 multiplied by itself 6 times, which equals one million.AgentResult(stop_reason='end_turn', message={'role': 'assistant', 'content': [{'text': '10^6 = 1,000,000\n\nThis represents 10 multiplied by itself 6 times, which equals one million.'}]}, metrics=EventLoopMetrics(cycle_count=2, tool_metrics={'calculator': ToolMetrics(tool={'toolUseId': 'tooluse_FV00wvpRRmK9mYNFo8ax-Q', 'name': 'calculator', 'input': {'prompt': '10^6'}}, call_count=1, success_count=1, error_count=0, total_time=2.747351884841919)}, cycle_durations=[1.717027187347412], traces=[<strands.telemetry.metrics.Trace object at 0x1123c4ec0>, <strands.telemetry.metrics.Trace object at 0x1124e76f0>], accumulated_usage={'inputTokens': 885, 'outputTokens': 99, 'totalTokens': 984}, accumulated_metrics={'latencyMs': 3482}), state={}, interrupts=None, structured_output=None)
>>> 
>>> print(agent.messages)
[{'role': 'user', 'content': [{'text': 'Show me 10 ^ 6'}]}, {'role': 'assistant', 'content': [{'text': "I'll calculate 10^6 for you."}, {'toolUse': {'toolUseId': 'tooluse_FV00wvpRRmK9mYNFo8ax-Q', 'name': 'calculator', 'input': {'prompt': '10^6'}}}]}, {'role': 'user', 'content': [{'toolResult': {'toolUseId': 'tooluse_FV00wvpRRmK9mYNFo8ax-Q', 'status': 'success', 'content': [{'text': '10^6 = 1,000,000\n\nThis represents 10 multiplied by itself 6 times, which equals one million.\n\n'}]}}]}, {'role': 'assistant', 'content': [{'text': '10^6 = 1,000,000\n\nThis represents 10 multiplied by itself 6 times, which equals one million.'}]}]

Standalone invocation of A2AAgent objects also works:

a2a_agent("Show me 10 ^ 6")

AgentResult(stop_reason='end_turn', message={'role': 'assistant', 'content': [{'text': '10^6 = 1,000,000 (one million)\n'}]}, metrics=EventLoopMetrics(cycle_count=0, tool_metrics={}, cycle_durations=[], traces=[], accumulated_usage={'inputTokens': 0, 'outputTokens': 0, 'totalTokens': 0}, accumulated_metrics={'latencyMs': 0}), state={}, interrupts=None, structured_output=None)

Follow-ups:

Related Issues

#907

Documentation PR

TODO

Type of Change

New feature

Testing

How have you tested the change? Verify that the changes do not break functionality or introduce warnings in consuming repositories: agents-docs, agents-tools, agents-cli

  • I ran hatch run prepare

Checklist

  • I have read the CONTRIBUTING document
  • I have added any necessary tests that prove my fix is effective or my feature works
  • [TODO] I have updated the documentation accordingly
  • [TODO] I have added an appropriate example to the documentation to outline the feature, or no new docs are needed
  • My changes generate no new warnings
  • Any dependent changes have been merged and published

By submitting this pull request, I confirm that you can use, modify, copy, and redistribute this contribution, under the terms of your choice.

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codecov bot commented Nov 13, 2025 •
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Codecov Report

❌ Patch coverage is 75.47170% with 39 lines in your changes missing coverage. Please review.

Files with missing lines Patch % Lines
src/strands/agent/a2a_agent.py 78.35% 15 Missing and 6 partials ⚠️
src/strands/multiagent/a2a/converters.py 67.27% 8 Missing and 10 partials ⚠️

📢 Thoughts on this report? Let us know!

mkmeral
mkmeral reviewed Nov 13, 2025
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@github-actions github-actions bot added size/l and removed size/l labels Nov 13, 2025
@github-actions github-actions bot added size/l and removed size/l labels Nov 13, 2025
mkmeral
mkmeral previously approved these changes Nov 14, 2025
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mkmeral
mkmeral reviewed Nov 14, 2025
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@mkmeral mkmeral self-requested a review November 14, 2025 20:49
@github-actions github-actions bot added size/l and removed size/l labels Nov 18, 2025
@github-actions github-actions bot added size/l and removed size/l labels Nov 18, 2025
@cagataycali
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cagataycali commented Nov 18, 2025

Can we also support parent agent's streaming support with callback_handler in a2a_client tool in strands-agents/tools?

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@awsarron @cagataycali @mkmeral