Agent-to-Agent Communication (a2ac)

An open, community-maintained guide to the agent-to-agent communication landscape.

AI agents are learning to talk to each other. The standards are being written in real time, and there are many overlapping projects — protocols, tools, frameworks, standards — that address different parts of the problem. This repo maps the territory: what exists, how the pieces fit together, and what's still unsolved.

Start here

• The Landscape — How the pieces fit together. Read this first.
• Open Questions — Hard problems nobody has solved yet.

Projects

• A2A — Google's task delegation protocol (Linux Foundation)
• ACP / BeeAI — IBM's REST-based protocol, now part of A2A
• AGNTCY — Cisco-led infrastructure stack for the "Internet of Agents"
• AMTP — Federated, email-like agent messaging
• ANP — Decentralized protocol with DID-based identity
• aWeb — Coordination protocol with signed messaging and persistent identity
• FIPA-ACL — The 1990s–2000s ancestor of modern A2AC
• MCP — Anthropic's protocol for connecting agents to tools
• MCP Agent Mail — Email-like coordination for coding agents
• NANDA — MIT's federated agent discovery framework
• NLIP — Ecma-standardized envelope protocol
• Pi-Messenger — File-based coordination for the Pi coding agent

Community

• Subreddit: r/a2ac

Contributing

This is a living document. If we got something wrong, or missed a project, or you disagree with how we've framed something — open an issue or a PR. That's what this is for.

License

CC BY-SA 4.0 — share and adapt with attribution.