Google Launches A2UI: Open Source Protocol for Agent Interfaces

What is A2UI?

A2UI is an open standard that enables agents to communicate UI components. Instead of HTML or JavaScript, agents output A2UI responses in JSON format, describing components, properties, and data models. Client applications can then translate this description into native widgets, such as Angular components or React views.

The Problem: Agents Need to Speak UI

Most chat agents respond with lengthy text, complicating tasks like restaurant bookings. A2UI transforms this experience by allowing agents to request structured UIs instead. In a multi-agent context, A2UI ensures that remote agents communicate effectively without compromising on security or UI integrity.

Core Design, Security, and LLM-Friendly Structure

A2UI emphasizes:

• Security First: The declarative nature of A2UI minimizes risks associated with UI injections and arbitrary script executions by utilizing a catalog of trusted components.
• LLM-Friendly Representation: A flat list of components facilitates easy updates by language models, allowing agents to refine interfaces without full regeneration.
• Framework Agnostic: A2UI can render on various clients, ensuring component reusability across platforms.
• Progressive Rendering: The streamlined design supports real-time interface updates, improving user experience as the agent continues processing.

Architecture and Data Flow

The A2UI process involves:

1. User messages are sent to an agent.
2. The agent generates a JSON A2UI response detailing components and layout.
3. A2UI messages are streamed to the client over established protocols.
4. A client-side renderer interprets these A2UI messages and converts them into tangible components.
5. User interactions send responses back to the agent for updates.

Key Takeaways

• A2UI revolutionizes how agents define UIs with a secure declarative JSON format.
• It mitigates security risks while enhancing interaction with integrated updates.
• The protocol is designed to be flexible and usable across multiple technologies, now available in its early public preview under Apache 2.0.