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Agent-to-Agent Protocol (A2A)

protocol
Trial

Update 07/2026 (assess → trial): A2A has matured from a Google-backed proposal into an industry standard under neutral governance and is now worth trialling where agents from different vendors or teams need to interoperate.

It moved to the Linux Foundation (mid 2025) and more than 150 organizations support the protocol, including AWS, Microsoft, SAP and ServiceNow (Linux Foundation, April 2026).

Real cross-vendor usage outside the big platforms is still hard to verify - for agent coordination inside a single system, a plain orchestration framework remains the simpler choice.

Updated link: A2A Project (Linux Foundation)

Assess

Agent-to-Agent (A2A) is an open, HTTP-based protocol that enables AI agents—built on different frameworks to coordinate tasks, exchange information, and collaborate. Backed by companies like Google, Salesforce, and LangChain, A2A standardizes inter-agent communication and discovery, preparing the way for modular, scalable multi-agent systems. This protocol is especially suitable when agents must operate independently but collaborate via clearly defined interfaces.

While MCP standardizes LLM-to-environment interaction, A2A focuses on agent-to-agent coordination. These protocols are complementary: MCP enables agents to reason with tools and context, while A2A enables those agents to talk to each other.

Key Concepts

  • A2A introduces three core actors: User (initiates requests), A2A Client (that makes requests on the user's behalf) and A2A Server (remote agent that fulfills requests and returns results)
  • AgentCard: JSON descriptor of an agent’s identity, capabilities, skills, endpoint, and auth requirements.
  • Discovery: Agents can be found via .well-known URLs, registries, or static configuration.
  • Communication: JSON-RPC over HTTP(S) using tasks and artifacts. Supports:
    • Synchronous (sendTask)
    • Asynchronous polling
    • Streaming (SSE)
    • Push (webhooks)
  • Security: AgentCard-defined auth schemes (API keys, OAuth2)

Resources