Agent to Agent (A2A) protocol is an open standard protocol, designed to enable secure communication and collaboration between AI agents across different platforms.
Launched by google in April 2025 it has caught the eyes of all AI enthusiast and engineers around the globe due to its ability to seamlessly integrate different AI systems.
It’s like a universal language for Artificial intelligence assistants, allowing them to share knowledge, coordinately perform task and increase user experience.
A2A protocol is promoting collaborative environment between diverse AI systems, to boost creativity and efficiency in the development of advanced Gen AI solutions.
As a result, the A2A Protocol is set to transform the landscape of AI development, encouraging a more interconnected and dynamic ecosystem.
What is A2A protocol?
The A2A Protocol is an HTTP-based communication model that enables interoperable services between agents, facilitating seamless collaboration and data exchange.
It provides a standardized framework for agent interaction, ensuring consistent communication and scalability in multi-agent systems.
Each agent exposes an “Agent Card” — a machine-readable JSON descriptor detailing its identity, capabilities, endpoints, and authentication requirements.
Agents use this information exposed in Agent Card to Discover capabilities of other agent and exchange message to negotiate task.
A2A utilizes JSON-RPC for message exchange, providing a language-independent way for remote procedure calls with JSON. This keeps A2A simple while managing complex agent interactions.
The protocol uses HTTP as its main transport layer, which builds on standard web communication. This makes A2A easy to integrate with existing systems and development tools.
It also includes SSE (Server-Sent Events) that allows a remote agent to stream updates to clients as work progresses.
A2A Architecture and Components
- Agent Card: A JSON file describing an agent’s capabilities, skills, endpoint URL, and authentication requirements that is used by clients to discovery.
- A2A Server: An agent exposing HTTP endpoint that implements the A2A protocol. It receives request from client and perform task
- A2A Client: An application or agent that requires to access the service of other agent. It sends requests to an A2A Server’s URL.
- Task: A Task is initiated by a client by sending a message to the server. They have unique IDs and progress through states.
- Message: Represents communication turns between the client and the agent.
- Part: The fundamental content unit found within a
Message. It Can be Text part, file part, or Data Part. - Artifact: Represents the outputs produced by the agent while executing a task.
- Streaming: For long-running tasks, servers supporting Server-Sent Events (SSE) sends update events providing real time update on the progress.
- Push Notification: A2A Protocol allow servers to send proactive task updates to a specified webhook URL provided by the client.
How A2A works?
A2A’s basic architecture centers on two agents working together. Client agents create and send tasks to the right remote agents. Remote agents process tasks and return information or performs actions.
Agents work on their own and don’t share memory or tools by default. They share information through structured messages.
First, a client agent spots a task for which it requires external support, Now it will perform capabilities discovery by looking for the agent to perform the operation based on their Agent Card.
Agent Cards are JSON documents that outline an agent’s capabilities, endpoints, supported message types, and authentication methods for clear and efficient communication.
After discovering, the Client agent creates and sends a task request to the remote agent, which processes the request and return a response Artifact.
Real-World Use Cases
1) Travel Agent Using A2A
- A user ask the bot: “Find the cheapest flight to Paris this Friday.”
- The travel agent delegates via A2A:
- Flight search to different Airline’s booking agent.
- Price comparison to an aggregator agent.
- Booking to the selected airline’s API agent.
2) E-commerce Shopping Assistant Using A2A
- A user asks the bot: “Order a phone under, 25000 with the best camera and display ”
- The Shopping Assistant use A2A to connect to different e-commerce site agents.
- Get the list of different mobile phone using different e-commerce site agents.
- Uses a feature comparison agent to identify the best camera and display phone.
- Ordering to the selected mobile phone using online store’s ordering API agent.
3) Customer Support Bot Using A2A
- A user messages the support bot: “Can I exchange this item? Also, is it in stock near me?”
- The support bot delegates via A2A:
- Exchange policy query to an exchange bot.
- Inventory check to a live stock agent.
- Shipping estimate to a logistics agent.
4) Smart Car Assistant
- Driver says: “Find the cheapest nearby charging station.”
- The in-car assistant uses A2A to:
- Locate stations with a location agent.
- Compare rates via an energy provider agent.
5) Event Planning Assistant Using A2A
- User says: “Plan a product launch event for next Friday evening.”
- The AI assistant uses A2A to coordinate across diverse agents:
- Venue Booking Agent – Finds available event spaces nearby.
- Marketing Agent – Schedules email invites and social media posts.
- Media Agent – Books a videographer and live-streaming setup.
- Catering Agent – Contacts food vendors for menu and pricing.
Conclusion
A2A enables AI agents from different platforms to work together through a common protocol, simplifying collaboration and boosting interoperability.
It supports complex task delegation by allowing agents to discover, communicate, and coordinate actions using structured messages and Agent Cards.
Furthermore, it enhances collaboration among agents, ensuring that tasks are executed efficiently and effectively.
Features like Server-Sent Events and webhook-based push notifications provide real-time task progress, consequently, they improve responsiveness and transparency.
With HTTP and JSON-RPC at its core, A2A is easy to adopt and integrate into existing systems, making multi-agent collaboration scalable and efficient.
A2A is shaping the future of AI by fostering a connected ecosystem where diverse agents can share capabilities, automate workflows, and enhance user experiences.
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