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MCP Apps: Extending servers with interactive user interfaces

blog.modelcontextprotocol.io

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Re: MCP Apps: Extending servers with interactive user interfaces

#91

Post by yunwal »

CuriouslyC wrote: post #34
emilsedgh wrote: post #4

I dont think people realize how important this is. If one of the vendors manages to get their protocol to become the target platform (eg oai and app sdk), that is essentially their vendor lock in to become the next iOS/Android. Private API’s or EEE strategies are gonna be something to keep an eye for and i wish regulators would step in to prevent them before its too late.

This is so backwards it's scary. Having a chatbot that drives websites inside of it is such an attempted monopolist play. Having a system agent that can interact with apps via API without being connected to the app is the pattern that's both elegant and preserves freedom.

I don't see how this is a step down from existing web applications. Should companies building web applications not be opinionated about their user interfaces? When I look at Notion, I should just get any view of the data inside it, regardless of whether it's the same view as my coworker gets? How is this preferable?

> Having a system agent that can interact with apps via API without being connected to the app is the pattern that's both elegant and preserves freedom

Does this prevent anyone from doing that?

Re: MCP Apps: Extending servers with interactive user interfaces

#92

Post by tyfon »

woleium wrote: post #87
greatgib wrote: post #85

When you think about that, without AI, simple automation could do most of what we would need if app and webapp providers would have been to provide interface. Were instead the big fight was to prevent scraping and to get your info in any other way than being forced to use the crappy app. Like for banking.

many banks have api access now, but maybe only for business accounts?

In Europe we have the PSD2 open banking [1] directive which essentially gives developers a standard api access to banking operations on behalf of a user.

It is a requirement for banks to implement this and the FSA will be on your neck if you are not compliant with the standard.

[1] https://finance.ec.europa.eu/regulation-and-supervision/fina...

Re: MCP Apps: Extending servers with interactive user interfaces

#93

Post by vidarh »

mindwok wrote: post #18

It'll be interesting to see how this goes, but my first impression is that it's actually not where we want to go. One of the cool things about MCP (or even just tool calling) is that the LLM on top of a tool provides a highly flexible and dynamic interface to traditionally static tools. I love being able to type "make an iptables rule that opens 443" instead of having to dig out the man page and remember how to do th…

MCP has already drastically lost utility already thanks to skills - for most things it is easier to just hand the model a CLI that it can run.

I'd imagine the same thing will happen here: It will prove more flexible to not push the model (and user) towards a UI that may not match what the user is trying to accomplish.

To me this seems like something I categorically don't want unless it is purely advisory.

Re: MCP Apps: Extending servers with interactive user interfaces

#94

Post by 0x696C6961 »

degamad wrote: post #31
neoden wrote: post #17

Earlier quoted context omitted.

MCP is already deterministic. What's huge about it is that it has automatic API discovery and integration built-in. It's a bit rough yet but I think we will only see how it's getting improved more and more.

> automatic API discovery and integration So, WSDL?

You really want to use WSDL? OpenAPI v3 would be a much better fit. But it has a tone of features that are completely unnecessary for this use-case. What if we just stripped it down to input and output json schemas? Oh wait ... we just invented MCP.

Re: MCP Apps: Extending servers with interactive user interfaces

#95

Post by mercury24aug »

iLoveOncall wrote: post #5
mercury24aug wrote: post #2

Looks like OpenAI, Anthropic, and the MCP-UI team actually worked together on a common standard for MCP Apps: https://blog.modelcontextprotocol.io/posts/2025-11-21-mcp-ap... Honestly, I think the biggest friction for MCP adoption has been how un-userfriendly it is. It’s great for devs, but not the average users. Users don't always want to chat, sometimes they just want to click a button or adjust a slider. This feels…

Who wants a button that has indeterministic actions?

AI fills in a form, and you want to adjust the form before clicking submit. How often do you have to adjust AI's answer vs accepting it as is

Re: MCP Apps: Extending servers with interactive user interfaces

#96

Post by mercury24aug »

stingraycharles wrote: post #14
iLoveOncall wrote: post #5

Earlier quoted context omitted.

Who wants a button that has indeterministic actions?

Unless the MCP server itself has an LLM call inside of it (rare), the MCP server is pretty deterministic. It’s the AI that invokes it that’s actually indeterministic, but the user is already using that.

This is a very strict definition of MCP. An agent (with LLM call inside) can be an MCP. Event a UI component can be an MCP.

Re: MCP Apps: Extending servers with interactive user interfaces

#97

Post by mercury24aug »

mindwok wrote: post #18

It'll be interesting to see how this goes, but my first impression is that it's actually not where we want to go. One of the cool things about MCP (or even just tool calling) is that the LLM on top of a tool provides a highly flexible and dynamic interface to traditionally static tools. I love being able to type "make an iptables rule that opens 443" instead of having to dig out the man page and remember how to do th…

Giving LLM the ability to generate UI is a cool concept, but our models are not there yet. MCP Apps can be extremely powerful, for example, you can play Doom inside ChatGPT: https://x.com/rauchg/status/1978235161398673553?s=20

I don't think we can generate anywhere close to this kind of UI just yet.

We built https://usefractal.dev/ to make it easier for people to build ChatGPT Apps (they are technically MCP Apps) so I have seen the use cases. Most of these use cases LLM cannot generate the UI on the fly.

Re: MCP Apps: Extending servers with interactive user interfaces

#98

Post by beders »

mbreese wrote: post #70

I don’t get it. I like MCP as an interface in general, but I don’t understand the use-case they present. For those of you here who like this idea, what is the killer use case? To me, this looks less like UI interactions and more like the MCP equivalent of maintaining state. You start your program and “click” buttons until you get the desired result, maintaining a constant state between interactions. Isn’t that curren…

This is the first wave of a new generation of Apps which has the potential to replace/enhance the majority of e-commerce websites.

I wouldn't underestimate it - it's the hammer can break up the information silos we've built up around websites/apps.

Why prompt Gertrude(tm) on Ramazon for a specific thing you need, if you can ask ChatGPT to find you said thing along with UIs to purchase it across all e-commerce platforms that agree to play in this market?

Re: MCP Apps: Extending servers with interactive user interfaces

#99

Post by johndevor »

mindwok wrote: post #18

It'll be interesting to see how this goes, but my first impression is that it's actually not where we want to go. One of the cool things about MCP (or even just tool calling) is that the LLM on top of a tool provides a highly flexible and dynamic interface to traditionally static tools. I love being able to type "make an iptables rule that opens 443" instead of having to dig out the man page and remember how to do th…

That's what we're doing at Hallway (https://hallway.com).

UIs should be fully remix-able and not set by the datasource/SaaS. So we built out a system to allow users to use the standard UI or remix apps as they want. Like Val.town, but with a flexible UX/workspace layer. Come check us out!

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