Live data from Hacker News

MCP Apps: Extending servers with interactive user interfaces

blog.modelcontextprotocol.io

101–110 of 124 posts

Re: MCP Apps: Extending servers with interactive user interfaces

#101
post #43

We already have AG-UI [0], which has been implemented by frameworks like Microsoft agent framework, pydantic AI and llamaindex. I guess they'll just have to duplicate functionality. Sigh. [0] https://docs.ag-ui.com/introduction

We had AG-UI. I'd say CopilotKit and AssistantUI (YC W25) are now Sherlocked

?

Re: MCP Apps: Extending servers with interactive user interfaces

#102
post #26

Earlier quoted context omitted.

I wonder how long it'll take you to figure out that you're trying to reinvent deterministic APIs.

Or just APIs in general. MCP is incredibly vibe-coded. We know how to make APIs. We know how to make two-way communications. And yet "let's invent new terminology that makes little sense and awkward workarounds on top of unidirectional protocols and call it the best thing since sliced cheese".

MCP is not just providing an API, it’s providing a client that uses that API.

And it does so in a standard way so that my client is available across AI providers. My users can install my client from an ordained URL without getting phished, or the LLM asking them to enter an API key.

What’s the alternative? Providing a sandbox to execute arbitrary code and make API calls? Having an LLM implement OAuth on the fly when it needs to make an API call?

MCP has a place.

Re: MCP Apps: Extending servers with interactive user interfaces

#103
post #69

Meta note: I really detest authors using cryptobro terminology “A dropped” and “B is huge” for anything technical. It immediately smells of script kiddies or their latest reincarnation.

Well the cryptobros moved into AI so not surprising.

I know because we are getting 3-4 spam messages per day on our discord server from various developers with previous experience in crypto now looking for opportunities in the agentic AI development space.

Re: MCP Apps: Extending servers with interactive user interfaces

#104
post #26

Earlier quoted context omitted.

Or just APIs in general. MCP is incredibly vibe-coded. We know how to make APIs. We know how to make two-way communications. And yet "let's invent new terminology that makes little sense and awkward workarounds on top of unidirectional protocols and call it the best thing since sliced cheese".

MCP is not just providing an API, it’s providing a client that uses that API. And it does so in a standard way so that my client is available across AI providers. My users can install my client from an ordained URL without getting phished, or the LLM asking them to enter an API key. What’s the alternative? Providing a sandbox to execute arbitrary code and make API calls? Having an LLM implement OAuth on the fly when…

> MCP is not just providing an API

It does just provide an API. Your client may have a way to talk to some software via MCP protocol. You know, like a client can talk to a server exposing an endpoint via an API.

> And it does so in a standard way so that my client is available across AI providers.

As in: it's an API on a port with a schema that a certain subset of software understands.

> What’s the alternative? Providing a sandbox to execute arbitrary code and make API calls?

MCP is a protocol. It couldn't care less what you do with your "tool" calls. Vast majority of clients and servers don't run in any sandbox at all. Because MCP is a protocol, not a docker container.

> Having an LLM implement OAuth on the fly when it needs to make an API call?

Yes, MCP has also a bolted-on authorisation that they didn't even think of when they vibe-coded the protocol. And at least finally there was some adult in the room that said "perhaps you should actually use a standardised way to do this". You know, like all other APIs get OAuth (and other types) of authorisations.

Re: MCP Apps: Extending servers with interactive user interfaces

#105
post #81
post #74

Earlier quoted context omitted.

If there is no file system where do the MCP definitions live and how are the agents aware of them? How are your end users aware of these definitions? There has to be a file somewhere.

> where do the MCP definitions What concretely do you mean be definitions? If you mean the configuration of the entry points similar to a .mcp.json for Claude Code, they can exist in any form, but ultimately, that only contains the endpoints of MCP servers (the entry points for discovery for each of the MCP servers). If you mean the definitions of what tools are part of what MCP server (= the meat of what is involved…

How is that different then an OpenAPI definition?

Re: MCP Apps: Extending servers with interactive user interfaces

#106
One thing I like about the current AI craze is that several services start to provide user-oriented services again, like 90s and 00s. Search engine for AI returning only relevant results (no ads and promotions), online stores showing only relevant items, news articles in non-clickbait, clear and concise style.

I'm not confident the current AI craze will be net positive for humanity. But one possible good outcome could be that many people prefer simple chat UI to interact with services, most companies have to adopt them and are forced to provide simple, straight, no-nonsense content instead of what they want to sell, while LLMs are just commodity so unnamed Chinese companies can provide models as good as the one from the most VC-funded company so they can't enshittify the UX.

Re: MCP Apps: Extending servers with interactive user interfaces

#107
post #98
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 platfor…

because the secret is that the web runs on advertising/targeted recommendations. Brezos(tm) wants you to actively browse Ramazon so he can harvest your data, search patterns etc. Amazon and most sites like that are very not crawl friendly for this reason. Why would Brezos let Saltman get all the juicy preference data?

Re: MCP Apps: Extending servers with interactive user interfaces

#108
post #104

Earlier quoted context omitted.

MCP is not just providing an API, it’s providing a client that uses that API. And it does so in a standard way so that my client is available across AI providers. My users can install my client from an ordained URL without getting phished, or the LLM asking them to enter an API key. What’s the alternative? Providing a sandbox to execute arbitrary code and make API calls? Having an LLM implement OAuth on the fly when…

> MCP is not just providing an API It does just provide an API. Your client may have a way to talk to some software via MCP protocol. You know, like a client can talk to a server exposing an endpoint via an API. > And it does so in a standard way so that my client is available across AI providers. As in: it's an API on a port with a schema that a certain subset of software understands. > What’s the alternative? Provi…

Perhaps confusingly, I’m referring to MCP as the sum of the protocol, a server adhering to the protocol, and clients adding support (e.g. “Connectors”).

The combination of these things turns into an ecosystem.

Re: MCP Apps: Extending servers with interactive user interfaces

#109
post #81

Earlier quoted context omitted.

> where do the MCP definitions What concretely do you mean be definitions? If you mean the configuration of the entry points similar to a .mcp.json for Claude Code, they can exist in any form, but ultimately, that only contains the endpoints of MCP servers (the entry points for discovery for each of the MCP servers). If you mean the definitions of what tools are part of what MCP server (= the meat of what is involved…

How is that different then an OpenAPI definition?

It conceptually isn't that far from OpenAPI defintions, but MCP do make certain affordances for making consumptions by LLMs easier.

But it certainly also differs by how they are typically consumed. In what software do you just provide your consuming client just an OpenAPI schema URL to be retrieved at runtime? In my experience, none.

Re: MCP Apps: Extending servers with interactive user interfaces

#110

Disclosure: I work at Anthropic, have worked on MCP I also think this is pretty big. I think a problem we collectively have right now is that getting MCP closer to real user flows is pretty hard and requires a lot of handholding. Ideally, most users of MCP wouldn't even know that MCP is a thing - the same way your average user of the web has no idea about DNS/HTTP/WebSockets. They just know that the browser helps the…

Can you potentially review utcp.io for seeing what MCP should have been to avoid context overloading? The dynamic tool search option and codemode to avoid loading all tools/servers into context seems like a better method imo.
Post reply on HN