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Ask HN: Who is using MCP in production?

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Re: Ask HN: Who is using MCP in production?

#41

Post by MitziMoto »

We use MCP in production for our customer facing voice agents. Our custom MCP server defines tools and resources that the voice agents need access to to interact with our customers. (E.g. scheduling appointments, checking order status, etc).

Now we can point any voice agent platform we choose -- eleven labs, vapi, pipecat, whatever -- at our custom MCP server and it instantly has an understanding of the tools available, their inputs, and how to use them.

Compared to the alternatives everyone on HN champions, like clis and APIs, this is a no brainer. I'm honestly not even sure what the realistic alternative would even be.

Am I supposed to package and distribute a cli to ElevenLabs and ask them to use it? Give them a full API spec to implement for me?

I give them an endpoint and credentials and their platform instantly knows how to talk to mine. No one at ElevenLabs knows or cares about our implementation details.

HN has trouble seeing past the "developer in a terminal coding with Claude Code" use case for using AI. Real production agents have use cases that are very different!

When you don't own every piece of an integration with another system, there needs to be a well defined standard. That's what MCP provides.

Re: Ask HN: Who is using MCP in production?

#43

Post by denkmoon »

MitziMoto wrote: post #41

We use MCP in production for our customer facing voice agents. Our custom MCP server defines tools and resources that the voice agents need access to to interact with our customers. (E.g. scheduling appointments, checking order status, etc). Now we can point any voice agent platform we choose -- eleven labs, vapi, pipecat, whatever -- at our custom MCP server and it instantly has an understanding of the tools availab…

Excuse me for being dense but I'd love to know more, if you can share. So you offer a voice agent for checking appointments and orders and stuff, is that through your app or website or something? So you make a button in your app which says "talk to our AI", and you've got the button set up so that it can send the customer's input query, along with a bit of text saying "our MCP is here, use it to answer the query", to any one of the voice agent providers? then you get some audio data in return that you play to the user?

Re: Ask HN: Who is using MCP in production?

#44

Post by insin »

I work on an F100's internal, vendor/model-independent LLM chat app whose agent runs in your browser, so CLI isn't an option, direct API is out as the agent deliberately doesn't have any tools for hitting arbitrary URLs and it can't access the network via its iframe-sandboxed code execution tool, so we use MCP in the harness to let it do third-party things, with e.g. Atlassian and GitHub MCP servers pre-configured and support for BYO MCP if there are compatible third-party servers you want to use, or are running your own locally to provide tools to let it do things on your machine (it can already be given R/W access to your local filesystem via showDirectoryPicker()).

The biggest issues are usually that a third-party MCP server you're trying to use either has misconfigured CORS so the browser can't hit it, has a bespoke OAuth setup which doesn't work with @modelcontextprotocol/client, or they don't support Dynamic Client Registration (DCR) so you can't just point at it and use it. It's nice when none of these apply and it Just Works, the user can auth easily with the third-party and refresh tokens automatically handled in the background by the client.

That's the advantage, really - you didn't have to define the tools yourself, auth is handled for you, and the agent doesn't need to (and can't) access credentials or tokens as it knows nothing about MCP.

Re: Ask HN: Who is using MCP in production?

#45

Post by RebeccaTheDev »

For what I am using it for, I recently wrote a little web app called Afterfeed [0] that lets you view backups from social media websites as a single unified timeline.

To put this into perspective, I was a voracious social media user for decades. For me, this is 25 years of data, close to 100,000 posts, spanning everything from LiveJournal in 2001 to Mastodon in 2026. But when put together, it is a timeline of my life.

As kind of a last minute idea, I added an MCP server because why not? Once I wired an LLM up to it, I could ask introspective questions and find new ways of looking at myself and my own history. Simple things like "what was I doing 10 years ago around this time?" to more complex things like researching past thought patterns.

[0] https://github.com/rebeccathedev/afterfeed/

Re: Ask HN: Who is using MCP in production?

#46

Post by MitziMoto »

denkmoon wrote: post #43
MitziMoto wrote: post #41

We use MCP in production for our customer facing voice agents. Our custom MCP server defines tools and resources that the voice agents need access to to interact with our customers. (E.g. scheduling appointments, checking order status, etc). Now we can point any voice agent platform we choose -- eleven labs, vapi, pipecat, whatever -- at our custom MCP server and it instantly has an understanding of the tools availab…

Excuse me for being dense but I'd love to know more, if you can share. So you offer a voice agent for checking appointments and orders and stuff, is that through your app or website or something? So you make a button in your app which says "talk to our AI", and you've got the button set up so that it can send the customer's input query, along with a bit of text saying "our MCP is here, use it to answer the query", to…

We use a Twilio integration to make it work over a real phone line, but it could just as well be an app or websocket connection in a browser.

Voice transport medium aside, the actual use case is not quite what you described.

Companies like Eleven Labs and Vapi provide a full end to end voice agent platform. They handle the STT -> LLM -> TTS pipeline and infrastructure for voice agents. Think of a customer talking to a virtual receptionist to schedule an appointment.

On the ElevenLabs platform, you provide them a system prompt (or an entire workflow/graph of system prompts) that instruct the voice agent on how to talk to the customer, tone, guardrails, how to answer specific questions, etc.

At some point we need that LLM agent, running on an infrastructure we don't control, to talk to our "CRM" (for simplicity sake). Enter MCP.

The MCP server we build and host supplies the "tools", like list_appointments, schedule_appointment, cancel_appointment-- whatever they may be.

When eleven Labs voice agent connects, it sees all the tools available and can use them per the instructions in the system prompt.

Re: Ask HN: Who is using MCP in production?

#47

Post by jdironman »

MitziMoto wrote: post #46
denkmoon wrote: post #43

Earlier quoted context omitted.

Excuse me for being dense but I'd love to know more, if you can share. So you offer a voice agent for checking appointments and orders and stuff, is that through your app or website or something? So you make a button in your app which says "talk to our AI", and you've got the button set up so that it can send the customer's input query, along with a bit of text saying "our MCP is here, use it to answer the query", to…

We use a Twilio integration to make it work over a real phone line, but it could just as well be an app or websocket connection in a browser. Voice transport medium aside, the actual use case is not quite what you described. Companies like Eleven Labs and Vapi provide a full end to end voice agent platform. They handle the STT -> LLM -> TTS pipeline and infrastructure for voice agents. Think of a customer talking to…

How is security handled in a situation like this? (I'll end up reading up on it). But I mean things like how does the API let a specific session with a specific user only surface information for that specific user from the available tooling?

Re: Ask HN: Who is using MCP in production?

#48

Post by cco »

jdironman wrote: post #47
MitziMoto wrote: post #46

Earlier quoted context omitted.

We use a Twilio integration to make it work over a real phone line, but it could just as well be an app or websocket connection in a browser. Voice transport medium aside, the actual use case is not quite what you described. Companies like Eleven Labs and Vapi provide a full end to end voice agent platform. They handle the STT -> LLM -> TTS pipeline and infrastructure for voice agents. Think of a customer talking to…

How is security handled in a situation like this? (I'll end up reading up on it). But I mean things like how does the API let a specific session with a specific user only surface information for that specific user from the available tooling?

Not the poster, but working on this right now.

The current framework that solves this the best right now is FiPA.

Establish identity the same way we always have, AS defines the challenges, the client (voice agent in this case) goes and gets them. OAuth from there!

Re: Ask HN: Who is using MCP in production?

#50

Post by blackqueeriroh »

muzani wrote: post #3

I used one for an AI tool that allows people to report bugs/feature request directly. It searches to make sure it isn't a duplicate, writes up the ticket, then submits it. Because it's a production tool, we want the cheapest possible one without it being too inaccurate. If you used a API etc, you'd end up building what's effectively a MCP-like adapter on top of it anyway so it could communicate in natural language in…

Atlassian’s MCP is phenomenal and they e had theirs longer than Linear
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