A2A (Agent2Agent)

P2P Protocols

Open protocol standard enabling interoperability between independent AI agents across organizational boundaries, frameworks, and vendors. Defines AgentCards (JSON capability advertisements), task lifecycle management, and JSON-RPC 2.0 over HTTP/HTTPS with SSE streaming. Agents discover each other's capabilities, negotiate interaction modalities, and collaborate on tasks without exposing internal state, memory, or tools. Designed to complement MCP (MCP connects agents to tools; A2A connects agents to agents). Originated at Google April 2025; donated to Linux Foundation June 2025; 150+ supporting organizations.

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Details

License Apache 2.0
Dev Status Released
Owner Linux Foundation (A2A Project, since June 23, 2025); originally created by Google
Country USA
Start Year 2025
Stack Python, TypeScript, LangGraph, CrewAI, Google ADK, BeeAI, Semantic Kernel
Funding Foundation
Last Investigated Jan 15, 2026

Use Case Domains

Co-Creation & Knowledge Events & Coordination

Affordances

Interoperable formats

P2P Protocol Attributes

P2P Architecture Client-server (A2A Client delegates tasks to A2A Server/remote agent); not a mesh topology
Overlay Network N/A — HTTP endpoint discovery via AgentCard URL
Content Addressing No
Local-First No
E2EE Yes — HTTPS with TLS required in production; agent internal state not exposed to peers
CRDTs Lib N/A
Byzantine Fault Tolerance N/A — no distributed consensus; task lifecycle managed by individual agents
Signature Yes — OAuth 2.0 / OIDC tokens; signed AgentCards (v0.3+); mTLS
Permissions OAuth 2.0 / OIDC (token-based); API Key; mTLS
Semantic Web Compatability No
Smart Contract No (protocol layer; no smart contract component)
Protocol Stack Position Application-layer (built on HTTP/HTTPS)
Asset / Value Embedding None — A2A is a communication protocol; value/payment handled by complementary protocols such as x402
Protocol Maturity / Standardization Production / Linux Foundation Open Standard — v0.3 specification released; 150+ supporting organizations including AWS, Cisco, Microsoft, Salesforce, SAP, ServiceNow; Apache 2.0; not yet submitted to IETF or W3C