Editing Agent-to-Agent Protocol

{{Infobox protocol
| name            = Agent-to-Agent Protocol
| developer       = [[wp:Google|Google]]
| status          = Stable
| first_published = April 2025
| transport       = [[wp:HTTPS|HTTPS]]
| encoding        = [[wp:JSON-RPC|JSON-RPC 2.0]], [[wp:Server-sent events|SSE]]
| license         = [[wp:Apache License|Apache 2.0]]
| website         = https://google.github.io/A2A
| repository      = https://github.com/google/A2A
}}

The '''Agent-to-Agent Protocol''' ('''A2A''') is an open standard developed by [[wp:Google|Google]] for enabling communication between autonomous [[wp:Intelligent agent|AI agents]]. Launched in April 2025 at Google Cloud Next '25, A2A provides a standardized way for agents to discover each other's capabilities, exchange information, and coordinate actions across platforms.

== Overview ==

A2A addresses the challenge of [[wp:Multi-agent_system|agent interoperability]] in enterprise environments where multiple specialized agents from different vendors need to collaborate. It enables agents to work together regardless of their underlying framework or technology stack, building on concepts from traditional [[wp:Agent_Communications_Language|Agent Communications Languages]].

=== Design principles ===

Google designed A2A around five key principles:

# '''Embrace agentic capabilities''' – Enable natural multi-agent collaboration without limiting agents to simple tools
# '''Build on existing standards''' – Use HTTP, SSE, and JSON-RPC for easy integration
# '''Secure by default''' – Enterprise-grade authentication and authorization
# '''Support for long-running tasks''' – Handle tasks that may take hours or days
# '''Modality agnostic''' – Support text, audio, and video streaming

== Architecture ==

A2A follows a client-server model:

=== Client Agent ===

The client agent initiates interactions by sending task requests to remote agents. It is responsible for discovering suitable agents, managing authentication, and coordinating workflows.

=== Remote Agent ===

Remote agents receive and process task requests. They advertise their capabilities via Agent Cards and handle authorization for incoming requests.

== Technical specification ==

=== Agent Cards ===

Agents advertise their capabilities using Agent Cards in JSON format:

{{Code example
| language = json
| caption  = Example Agent Card
| code     = {
  "name": "Travel Booking Agent",
  "description": "Books flights and hotels",
  "capabilities": [
    "flight_search",
    "hotel_booking",
    "itinerary_management"
  ],
  "endpoint": "https://travel.example.com/agent",
  "authentication": {
    "type": "oauth2"
  }
}
}}

=== Communication flow ===

# '''Discovery''' – Client agent identifies suitable remote agents via Agent Cards
# '''Authentication''' – Remote agent verifies client credentials
# '''Task execution''' – Agents exchange messages to complete the task
# '''Result delivery''' – Remote agent returns results to client

=== Security ===

A2A supports multiple authentication schemes:

* [[wp:OAuth|OAuth 2.0]]
* API keys
* Mutual [[wp:Transport Layer Security|TLS]] (mTLS)
* Scoped tokens for capability-specific access

== Adoption ==

A2A launched with support from over 50 technology partners, including:

* Technology companies: Atlassian, Box, Salesforce, SAP, ServiceNow
* Consulting firms: Accenture, Deloitte, McKinsey, PwC

The protocol is now managed under the [[wp:Linux Foundation|Linux Foundation]].

== Comparison with other protocols ==

{| class="wikitable"
|-
! Protocol !! Focus !! Relationship
|-
| [[Model Context Protocol|MCP]] || Tool integration || Complementary (vertical vs. horizontal)
|-
| [[Agent Communication Protocol|ACP]] || Local-first coordination || Alternative for edge/local scenarios
|-
| [[Agent Network Protocol|ANP]] || Decentralized internet-scale || Alternative with different architecture
|}

== See also ==

* [[Model Context Protocol]]
* [[Agent Communication Protocol]]
* [[Agent Network Protocol]]
* [[Multi-Agent Systems]]

== References ==

{{Reflist}}

== External links ==

* [https://google.github.io/A2A Official specification]
* [https://github.com/google/A2A GitHub repository]
* [https://developers.googleblog.com/en/a2a-a-new-era-of-agent-interoperability/ Launch announcement]

[[Category:Communication Protocols]]
[[Category:Agent Communication]]
[[Category:Google Specifications]]
[[Category:Multi-Agent Systems]]