Digital Lexicon Hub

An open protocol that lets AI agents from different vendors and frameworks discover each other, exchange messages and delegate tasks.

A2A lets companies connect agents from different vendors, such as a CRM agent and a procurement agent, without a custom integration for each pair, and makes each agent's skills and authentication explicit.

A sales agent reads a supplier agent's Agent Card, authenticates with OAuth, sends a task asking for a quote on 500 units, and receives streamed status updates until the task completes with a quote artifact.

Interoperability depends on vendor adoption and version alignment, and delegation between agents adds risks such as prompt injection through messages and unclear accountability for actions taken across organizations.

Each A2A server publishes an Agent Card, a JSON document listing identity, skills, endpoint and authentication requirements. Clients send messages made of parts and create tasks whose lifecycle ends as completed, failed, canceled or rejected, or pauses for input. The specification defines JSON-RPC, gRPC and HTTP+JSON bindings, Server-Sent Events for streaming and webhooks for push notifications. Google introduced A2A in April 2025 and moved it to the Linux Foundation in June 2025. It complements Model Context Protocol (MCP) in a Multi-Agent System.