Hacker News Reader

Comment by mbossie | Hacker News Reader

So there's MCP-UI, OpenAI's ChatKit widgets and now Google's A2UI, that I know of. And probably some more...

How many more variants are we introducing to solve the same problem. Sounds like a lot of wasted manhours to me.

I agree that it's annoying to have competing standards, but when dealing with a lot of unknowns it's better to allow divergence and exploration. It's a worse use of time to quibble over the best way to do things when we have no meaningful data yet to justify any decision. Companies need freedom to experiment on the best approach for all these new AI use cases. We'll then learn what is great/terrible in each approach. Over time, we should expect and encourage consolidation around a single set of standards.

> when dealing with a lot of unknowns it's better to allow divergence and exploration

I completely agree, though I'm personally sitting out all of these protocols/frameworks/libraries. In 6 months time half of them will have been abandoned, and the other half will have morphed into something very different and incompatible.

For the time being, I just build things from scratch, which–as others have noted¹–is actually not that difficult, gives you understanding of what goes on under the hood, and doesn't tie you to someone else's innovation pace (whether it's higher or lower).

¹ https://fly.io/blog/everyone-write-an-agent/

I recently heard that when automobiles were new the USA quickly ended up in a state with 80 competing manufacturing brands. In a couple decades, the market figured out what customers actually want and what styles and features mattered, and the competition ecosystem consolidated to 5 brands.

The same happened with GPUs in the 90s. When Jensen formed Nvidia there were 70 other companies selling Graphics Cards that you could put in a PCI slot. Now there are 2.

AGUI sounds similar: https://github.com/ag-ui-protocol/ag-ui

Same team! AGUI uses a2UI as the protocol under the hood.

Hi, one of the AG-UI authors here.

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

And thank you CopilotKit team!

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.

This provides a bit more detail on how they relate to each other

https://www.copilotkit.ai/ag-ui-and-a2ui

MCP-UI and OpenAI Apps are converging into the MCP Apps extension specification: https://blog.modelcontextprotocol.io/posts/2025-11-21-mcp-ap...

> Sounds like a lot of wasted manhours to me

Sounds like a lot of people got paid because of it. That's a win for them. It wasn't their decision, it was company decision to take part in the race. Most likely there will be more than 1 winner anyway.

I'm one of these people. We have to start working on the problem many months before the competition announces that they exist. So we are all just doing parallel evolution here. Everyone agrees that to sit and wait for a standard means you wouldn't waste energy, but you'd also have no influence.

Like you mentioned, its a good time to be employed.

Unlike many of those approaches which concern themselves with delivery of human-designed static UI, this seems to be a tool designed to support generative UIs. I personally think that's a non-starter and much prefer the more incremental "let the agent call a tool that renders a specific pre-made UI" approach of MCP UI/Apps, OpenAI Apps SDK, etc for now.

Legitimate curiosity - why?

Making an agent call a tool to manipulate a UI does feel like normal application development and an event driven interaction... I get that.

What else drives your preference?

We should make one new standard for everyone to use ...

Obligatory https://xkcd.com/927/

Oh yes. I send this all the time. And I also see the irony.

I can justify A2UI as doing something not otherwise accomplishable in the market today, but you saw how long the blog post was trying to explain that. :shrug:

Reply on news.ycombinator.com