Add A2A (Agent-to-Agent) protocol support by minorun365 · Pull Request #217 · aws/bedrock-agentcore-sdk-python

minorun365 · 2026-01-18T10:28:50Z

Summary

This PR adds support for the A2A (Agent-to-Agent) protocol, enabling agents to communicate with each other using the JSON-RPC 2.0 protocol.

New Features

BedrockAgentCoreA2AApp: A Starlette-based application class for hosting A2A agents
AgentCard & AgentSkill: Models for describing agent capabilities
@entrypoint decorator: For defining message handlers
JSON-RPC 2.0 support: Standard A2A protocol implementation on port 9000

New Files

src/bedrock_agentcore/runtime/a2a_app.py - Main A2A application class
src/bedrock_agentcore/runtime/a2a_models.py - A2A data models
tests/bedrock_agentcore/runtime/test_a2a_app.py - Unit tests for A2A app
tests/bedrock_agentcore/runtime/test_a2a_models.py - Unit tests for A2A models

Usage Example

from bedrock_agentcore.runtime import AgentCard, AgentSkill, BedrockAgentCoreA2AApp

agent_card = AgentCard(
    name="My Agent",
    description="A helpful assistant",
    version="1.0.0",
    skills=[AgentSkill(id="qa", name="Q&A", description="Answer questions")],
)

app = BedrockAgentCoreA2AApp(agent_card=agent_card)

@app.entrypoint
async def handle_message(request, context):
    user_text = request.params.get("message", {}).get("parts", [{}])[0].get("text", "")
    return {"artifacts": [{"parts": [{"kind": "text", "text": f"Response to: {user_text}"}]}]}

if __name__ == "__main__":
    app.run()

Test Plan

All 54 unit tests pass
Linter checks pass
Tested locally with curl commands
Deployed to AgentCore Runtime and verified working

@entrypoint

- Add BedrockAgentCoreA2AApp class for hosting A2A agents - Add A2A models (AgentCard, AgentSkill, JsonRpcRequest/Response, etc.) - Add @entrypoint decorator for message handling - Support JSON-RPC 2.0 protocol on port 9000 - Export A2A classes from runtime module - Add comprehensive unit tests (54 tests)

Moophic · 2026-03-02T20:25:18Z

@sundargthb,
Can we get this beautiful PR reviewed and merged please?

sundargthb · 2026-03-11T22:09:39Z

src/bedrock_agentcore/runtime/a2a_models.py

+from urllib.parse import quote
+
+
+class JsonRpcErrorCode(int, Enum):


the codes here match this page but contradicts with the A2A Protocol contract page.. need to check the valid range

sundargthb · 2026-03-11T22:13:47Z

src/bedrock_agentcore/runtime/a2a_app.py

+            return JSONResponse(card_dict)
+        except Exception as e:
+            self.logger.exception("Failed to serve Agent Card")
+            return JSONResponse({"error": str(e)}, status_code=500)


str(e) is passed directly into the JSON-RPC error response. ... internal exception details (paths, library errors, connection strings) can reach external agents ? the HTTP app.py has the same str(e) pattern — so this isn't new to the PR, it's consistent with existing code. But A2A is explicitly cross-organizational (A2A Enterprise Features)

sundargthb · 2026-03-11T22:15:19Z

src/bedrock_agentcore/runtime/a2a_app.py

+            self.logger.exception("Request failed (%.3fs)", duration)
+            return self._jsonrpc_error_response(
+                body.get("id") if "body" in dir() else None,
+                JsonRpcErrorCode.INTERNAL_ERROR,


same comment as _handle_agent_card..

sundargthb · 2026-03-11T22:20:08Z

src/bedrock_agentcore/runtime/a2a_app.py

+)
+
+
+class A2ARequestContextFormatter(logging.Formatter):


The HTTP app has @async_task, add_async_task()/complete_async_task(), and force_ping_status()/clear_forced_ping_status(). Without these, developers can't signal HealthyBusy during long-running agent workflows, which means the runtime may incorrectly scale down or over-route. Can either finish the port from app.py or remove the unused attributes/logic

Add missing A2A protocol standard error codes (-32001 to -32007) alongside existing AgentCore Runtime error codes (-32501 to -32505). The two sets serve different layers: protocol-level (task management) vs infrastructure-level (throttling, resource management). Added corresponding tests. Addresses review feedback on PR aws#217 regarding error code alignment between A2A protocol spec and AWS AgentCore documentation. https://claude.ai/code/session_01Fnc4LHzBPBej7FK7ooT2La

- Remove unused imports (JsonRpcRequest, pytest) in tests - Initialize body=None before try block; replace `"body" in dir()` with `body is not None` - Add `isinstance(body, dict)` guard so non-object JSON payloads return INVALID_REQUEST (-32600) instead of INTERNAL_ERROR (-32603) - Use `_convert_to_serializable()` / `_safe_serialize_to_json_string()` for both streaming and non-streaming paths so dataclass helpers (A2AArtifact, etc.) serialize correctly - Fall back to `request.base_url` when AGENTCORE_RUNTIME_URL is unset so the agent card always contains a reachable URL - Add tests for dataclass serialization (sync + streaming) and non-object payload rejection

minorun365 · 2026-03-12T07:39:01Z

@sundargthb Thanks for your review! Fixed it.

codecov-commenter · 2026-03-12T12:22:46Z

Codecov Report

❌ Patch coverage is 85.48813% with 55 lines in your changes missing coverage. Please review.
⚠️ Please upload report for BASE (main@52bc194). Learn more about missing BASE report.

Files with missing lines	Patch %	Lines
src/bedrock_agentcore/runtime/a2a_app.py	81.22%	34 Missing and 12 partials ⚠️
src/bedrock_agentcore/runtime/a2a_models.py	93.18%	3 Missing and 6 partials ⚠️

Additional details and impacted files

@@           Coverage Diff           @@
##             main     #217   +/-   ##
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  Branches        ?      664           
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  Misses          ?      240           
  Partials        ?      185

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minorun365 temporarily deployed to manual-approval January 18, 2026 10:29 — with GitHub Actions Inactive

sundargthb reviewed Mar 11, 2026

View reviewed changes

minorun365 requested a review from a team March 12, 2026 06:48

minorun365 requested a deployment to manual-approval March 12, 2026 06:48 — with GitHub Actions Waiting

minorun365 force-pushed the feature/a2a-protocol-support branch from 0a85319 to ee117a9 Compare March 12, 2026 07:30

minorun365 requested a deployment to manual-approval March 12, 2026 07:30 — with GitHub Actions Waiting

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Add A2A (Agent-to-Agent) protocol support#217

Add A2A (Agent-to-Agent) protocol support#217
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minorun365:feature/a2a-protocol-support

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		from urllib.parse import quote


		class JsonRpcErrorCode(int, Enum):

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minorun365 commented Jan 18, 2026

Summary

New Features

New Files

Usage Example

Test Plan

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Moophic commented Mar 2, 2026 •

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