Strands ships no A2A server integration, which turns out to be the easiest starting position of the three frameworks I used: you drop the agent behind the a2a-sdk reference routes and you are serving the protocol's own implementation.
The hard part was never Strands. It was AgentCore Runtime — a container contract that is narrow, mostly undocumented in one place, and different from every other runtime in the mesh.
I ran that agent alongside a Google ADK agent on Cloud Run and a Microsoft Agent Framework agent on Container Apps, all three answering the same research brief over A2A v1.0 to one coordinator. Everything below is the AWS side of it.
The code: github.com/xbill9/multicloud-a2a-subagent.
The contract, in one place
