Creativity · Agent Protocol
AG-UI — Agent-User Interaction Protocol
AG-UI (Agent-User Interaction protocol) is an open, event-based specification describing how an agent backend streams its internal state — thoughts, tool calls, intermediate outputs, status updates — to a front-end UI. Where A2A targets agent-to-agent and MCP targets agent-to-tool, AG-UI targets agent-to-user, standardising the shape of events so any UI can render any compliant agent's activity.
Protocol facts
- Sponsor
- CopilotKit + open community
- Status
- proposed
- Spec
- https://docs.ag-ui.com/
- Interop with
- A2A, MCP, LangGraph, CrewAI, server-sent events
Frequently asked questions
Why does the agent ecosystem need an agent-to-UI protocol?
Every framework currently invents its own event stream format. AG-UI standardises event types (tool_start, tool_result, thought, status, message) so a UI component built once can render any compliant agent.
How does AG-UI relate to A2A and MCP?
The three form a layered stack: MCP connects agents to tools, A2A connects agents to other agents, and AG-UI connects agents to the humans watching them work.
Is AG-UI tied to a specific framework?
No — AG-UI ships SDK adapters for major frameworks (LangGraph, CrewAI, OpenAI Agents, etc.) but the event schema itself is framework-neutral.
Sources
- AG-UI — docs.ag-ui.com — accessed 2026-04-20