Agent2Agent (A2A) Protocol

What is A2A Protocol?¶

The Agent2Agent (A2A) Protocol is an open standard designed to enable seamless communication and collaboration between AI agents.

In a world where agents are built using diverse frameworks and by different vendors, A2A provides a common language, breaking down silos and fostering interoperability.

Build with ADK (or any framework), equip with MCP (or any tool), and communicate with A2A, to remote agents, local agents, and humans.

Get started with Agent2Agent (A2A) Protocol¶

Video Intro in <8 min
Read the Introduction

Understand the core ideas behind A2A.

What is A2A?

Key Concepts
Dive into the Specification

Explore the detailed technical definition of the A2A protocol.

Protocol Specification
Follow the Tutorials

Build your first A2A-compliant agent with our step-by-step Python quickstart.

Python Tutorial
Explore Code Samples

See A2A in action with sample clients, servers, and agent framework integrations.

GitHub Samples
Download the SDK

Python

JavaScript

Java

C#/.NET

Golang

Why use the A2A Protocol¶

graph LR
    User(🧑‍💻 User) <--> ClientAgent(🤖 Client Agent)
    ClientAgent --> A2A1(**↔️ A2A**) --> RemoteAgent1(🤖 Remote Agent 1)
    ClientAgent --> A2A2(**↔️ A2A**) --> RemoteAgent2(🤖 Remote Agent 2)

    style User fill:#fdebd0,stroke:#e67e22,stroke-width:2px
    style ClientAgent fill:#d6eaf8,stroke:#3498db,stroke-width:2px
    style RemoteAgent1 fill:#d6eaf8,stroke:#3498db,stroke-width:2px
    style RemoteAgent2 fill:#d6eaf8,stroke:#3498db,stroke-width:2px
    style A2A1 fill:#ebedef,stroke:#909497,stroke-width:2px
    style A2A2 fill:#ebedef,stroke:#909497,stroke-width:2px

Interoperability

Connect agents built on different platforms (LangGraph, CrewAI, Semantic Kernel, custom solutions) to create powerful, composite AI systems.
Complex Workflows

Enable agents to delegate sub-tasks, exchange information, and coordinate actions to solve complex problems that a single agent cannot.
Secure & Opaque

Agents interact without needing to share internal memory, tools, or proprietary logic, ensuring security and preserving intellectual property.

How does A2A work with MCP?¶

A2A MCP Graphic

A2A and Model Context Protocol (MCP) are complementary standards for building robust agentic applications:

Model Context Protocol (MCP): Provides agent-to-tool communication. It's a complementary standard that standardizes how an agent connects to its tools, APIs, and resources to get information.
IBM ACP: Incorporated into the A2A Protocol
Cisco agntcy: A framework for building the internal logic of a single, complex agent system, often with a supervisor/expert structure.
A2A: Provides agent-to-agent communication. As a universal, decentralized standard, A2A acts as the public internet that allows ai agents—including those using MCP, or built with frameworks like agntcy—to interoperate, collaborate, and share their findings.