Tour of Agent Protocols: MCP, A2A, AG-UI, A2UI - Mete Atamel - NDC Copenhagen 2026
The talk provides a deep technical overview of four emerging protocols designed to standardize communication and interaction within complex AI agent systems: Model Context Protocol (MCP), Agent-to-Agent Protocol (A2A), Agent-User Interface Protocol (AG-UI), and Agent-to-UI Protocol (A2UI). These standards address the challenges of building interoperable agents that can access external tools, communicate with other agents across diverse frameworks, and generate rich user interfaces.
Key takeaways
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MCP Standardizes Tool/Context Access
18:03
MCP standardizes how Large Language Models (LLMs) access external functions (tools) and data (resources). Instead of one-to-one integrations, tools are wrapped into MCP servers, which can be accessed by an AI application via an MCP client. This architecture supports local (Standard IO) or remote (streamable HTTP transport) deployments.
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A2A Enables Inter-Agent Communication
23:50
A2A is an open protocol defining how agents running on different frameworks communicate. Agents expose their capabilities via a JSON metadata file called the 'agent card,' which details skills (functions), contact methods, and authentication schemes.
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AG-UI Standardizes Agent State Streaming
29:40
AG-UI is an event-based protocol designed to standardize how agent backends stream state updates to frontends, connecting the AI logic layer to the user interface.
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A2UI Standardizes Generative UI Output
32:30
A2UI is a generative protocol that standardizes how agents generate functional User Interface (UI) components (using JSON structures), moving beyond simple text or data output. It defines core messages like `create surface`, `update components`, and `update data model`.