I think AG UI is great if you are building the UI and the Agent at the same time and want a high bandwidth sync between them and the UI supports AG UI as an adaptor layer (they have done a lot of work making this easier for folks).
A2UI is most interesting for it's LLM generation options (not tools but structured output), it's remote message passing options (if you don't own the UI), and it's general-purpose-ness (same fairly simple standard which can work for many models, transports, and renderers).
They do fit nicely together. Sorry the naming conventions are complicated. There are 2 hard things in computer science: naming things, cache invalidation, off by one errors.
Introducing AG-UI; the Agent-User Interaction Protocol.
AG-UI is an open, lightweight, event-based protocol that standardizes how AI agents connect to fronted-end applications.
After a year of one-off, CopilotKit <> Agent frameworks collaborations, we decided to ship a standard, and open way for agents to connect to apps.
We are launching with day 0 integrations with LangChain, Mastra, CrewAI and AG2 with more partnerships on the way.
How AG-UI works:
- Creates a unified, two-way bridge between backend agents and frontend apps
- Works with any event transport (SSE, WebSockets, webhooks)
- Supports 16 standardized event types for common agent-user interactions
Where AG-UI fits in the agent protocol landscape:
- MCP: for agent←→tools communication
- A2A/ACP: for agent←→agent communication
- AG-UI: for agent←→human interaction in applications
We launched the protocol yesterday, and have been blown away by the reception. We have the first working group this Friday, to help expand and steer the direction of the protocol.
People use the same model / server for all queries not because it's sensible, but because it's simple. This brings the same simplicity to the far more optimal solution.
And great startup play too, by definition no incumbent can fill this role.
We are building CopilotKit = a framework + platform for building context-aware AI assistants into any application (not necessarily coding related applications).
Part of CopilotKit is about giving the Copilot / AI agents access to the application through a typed "inline realtime API". And to make ergonomics great for _our_ users, CopilotKit ships with hardcore type programming.
Cursor's Copilot (unrelated to CopilotKit) helped us write this type code (that's what went viral). And yes, GitHub Copilot is a mis-attribution.
I'm going to make a completely fresh alternative written from the ground up. When I'm done you can all find it easily because it's called CoPilot, shouldn't be hard to find.
By the way - we practice what we preach-
Copilots raise the bar (or the ceiling...) on human productivity - in every domain. Which is why we're building infrastructure to make building copilots easier...
What ideas do you think are still missing from today's Copilots?
I.e. suppose we were looking back at today's Copilots 5 years from now- besides better models, what else has changed?
AG-UI is a launch partner of A2UI, but it is a separate project by CopilotKit, not google.
We have a day-0 handshake between AG-UI & A2UI