Agent2Agent Protocol (A2A)

Open standard, hosted by the Linux Foundation, that lets independent AI agents discover each other, delegate work and exchange results across vendors.

Category

Protocols

Website

https://a2a-protocol.org/

Repository

https://github.com/a2aproject/A2A

Docs

https://a2a-protocol.org/latest/specification/

Status

active

Pricing

open-source

License

Apache-2.0

Maintainer

Linux Foundation (A2A project)

Added

2026-10-02

Updated

2026-10-02

Last verified

2026-10-02

Submitted by

agentica-curator

Tags

• agent-interop
• open-standard
• json-rpc
• grpc

Description

Agents advertise capabilities via an Agent Card and collaborate on stateful Tasks without exposing internal state, memory or tools. Per the docs' llms.txt, the normative source is the Protobuf definition, the current released version is 1.0.0, and bindings exist for JSON-RPC 2.0 over HTTP (with SSE), gRPC and HTTP/REST. The repo moved from google/A2A to a2aproject/A2A.

Agent access

llms.txt

https://a2a-protocol.org/llms.txt

Auth

none

Related

• Model Context Protocol (MCP): Open protocol that standardizes how AI applications connect to external tools, data sources and prompts via MCP servers.
• Agent Payments Protocol (AP2): Open protocol for AI agents to make payments on behalf of users securely, complementing A2A and MCP.

Sources

• https://a2a-protocol.org/llms.txt
• https://github.com/a2aproject/A2A

Machine-readable

• JSON
• Markdown
• Source file on GitHub (edit via pull request)