← Agentic Application Middleware
Read the original post ↗
A2A Extensions: Empowering Custom Agent Functionality- Google Developers Blog
9/9/2025 · Philip Stephens, Junjie Bu, Mike Smith, Chitra Venkatesh
What this post added
Introduces A2A Extensions as a mechanism to add custom, domain-specific functionalities to the A2A protocol. Details the 'helloworld' extension for timestamps, a Traceability Extension with `ResponseTrace` and `Step` types (`ToolInvocation`, `AgentInvocation`), Twilio's Latency Extension for voice agents, and Identity Machines' zero-trust handshakes. Mentions Ethereum's proposed ERC-8004 for a trust layer for AI agents.