---
title: "A2A"
type: "glossary term"
url: "https://aifordevs.org/glossary#a2a"
markdown: "https://aifordevs.org/glossary/a2a.md"
publisher: "AI for Devs"
license: "https://aifordevs.org/reuse"
attribution: "Credit AI for Devs and link to https://aifordevs.org/glossary#a2a"
also_known_as: "Agent2Agent protocol"
---

# A2A (Agent2Agent protocol)

A2A (Agent2Agent) is an open protocol, introduced by Google in April 2025, that lets agents built by different vendors discover each other, exchange tasks, and stream results. MCP connects an agent to tools and data, while A2A connects agents to other agents.

A remote agent publishes a JSON Agent Card at /.well-known/agent-card.json listing its skills, endpoint, and auth requirements. Work runs as a task with a defined lifecycle, so a long job can pause for input and report status. As of November 8, 2026, the spec is at version 1.0.0 with JSON-RPC, gRPC, and HTTP+JSON bindings, and A2A is a Growth Stage project at the Agentic AI Foundation.

## Example

A client fetches https://example.com/.well-known/agent-card.json, finds the skill it needs, and sends a message. The task that message starts moves from SUBMITTED to WORKING to COMPLETED.

## Source

[A2A Protocol specification](https://a2a-protocol.org/latest/specification/)

## Related terms

- [MCP](https://aifordevs.org/glossary#mcp)
- [Agent](https://aifordevs.org/glossary#agent)

## Cite this term

AI for Devs. "A2A." https://aifordevs.org/glossary#a2a

- Page: https://aifordevs.org/glossary#a2a
- Markdown: https://aifordevs.org/glossary/a2a.md
- Reuse: Quote or summarize with a link to this page. Terms: https://aifordevs.org/reuse
- Publisher: AI for Devs