MCP: An (Accidentally) Universal Plugin System

#1

Post by Stwerner » Sat, Jun 28, 2025, 2:22 PM UTC

MCP: An (Accidentally) Universal Plugin System
worksonmymachine.substack.com

Re: MCP: An (Accidentally) Universal Plugin System

#2

Post by roenxi » Sat, Jun 28, 2025, 2:31 PM UTC

... MCP is almost literally just a JSON schema and a "yo, this stuff exists" for AI. It is great to have it standardised and we're all very thankful not to be using XML but there just isn't that much there.

MCP is fulfilling the promise of AI agents being able to do their own thing. None of this is unintended, unforeseen or particularly dependent on the existence of MCP. It is exciting, the fact that AI has this capability captures the dawn of a new era. But the important thing in the picture isn't MCP - it is the power of the models themselves.

Re: MCP: An (Accidentally) Universal Plugin System

#3

Post by spiritplumber » Sat, Jun 28, 2025, 2:37 PM UTC

Yes, I'm old. Old enough to remember the MCP when he was just a chess program! He started small, and he'll end small!

Re: MCP: An (Accidentally) Universal Plugin System

#4

Post by jadar » Sat, Jun 28, 2025, 2:38 PM UTC

I don’t want to undermine the author’s enthusiasm for the universality of the MCP. But part of me can’t help wondering: isn’t this the idea of APIs in general? Replace MCP with REST and does that really change anything in the article? Or even an Operating System API? POSIX, anyone? Programs? Unix pipes? Yes, MCP is far simpler/universal than any of those things ended up being — but maybe the solution is to build simpler software on good fundamental abstractions rather than rebuilding the abstractions every time we want to do something new.

Re: MCP: An (Accidentally) Universal Plugin System

#5

Post by bayesianbot » Sat, Jun 28, 2025, 2:44 PM UTC

jadar wrote: post #4

I don’t want to undermine the author’s enthusiasm for the universality of the MCP. But part of me can’t help wondering: isn’t this the idea of APIs in general? Replace MCP with REST and does that really change anything in the article? Or even an Operating System API? POSIX, anyone? Programs? Unix pipes? Yes, MCP is far simpler/universal than any of those things ended up being — but maybe the solution is to build simp…

My first thought as well. But maybe at least people wanting to plug their apps to their AI forces developers to actually implement the interface, unlike APIs that are mostly unheard of in general population and thus not offered?

Re: MCP: An (Accidentally) Universal Plugin System

#6

Post by kvdveer » Sat, Jun 28, 2025, 2:46 PM UTC

jadar wrote: post #4

I don’t want to undermine the author’s enthusiasm for the universality of the MCP. But part of me can’t help wondering: isn’t this the idea of APIs in general? Replace MCP with REST and does that really change anything in the article? Or even an Operating System API? POSIX, anyone? Programs? Unix pipes? Yes, MCP is far simpler/universal than any of those things ended up being — but maybe the solution is to build simp…

The main difference between MCP and Rest is that MCP is self described from the very start. REST may have OpenAPI, but it is a later addon, and we haven't quite standardised on using it. The first step of exposing an MCP is describing it, for Rest is is an optional step that's often omitted.

Re: MCP: An (Accidentally) Universal Plugin System

#7

Post by light_hue_1 » Sat, Jun 28, 2025, 2:47 PM UTC

kvdveer wrote: post #6

jadar wrote: post #4

I don’t want to undermine the author’s enthusiasm for the universality of the MCP. But part of me can’t help wondering: isn’t this the idea of APIs in general? Replace MCP with REST and does that really change anything in the article? Or even an Operating System API? POSIX, anyone? Programs? Unix pipes? Yes, MCP is far simpler/universal than any of those things ended up being — but maybe the solution is to build simp…

The main difference between MCP and Rest is that MCP is self described from the very start. REST may have OpenAPI, but it is a later addon, and we haven't quite standardised on using it. The first step of exposing an MCP is describing it, for Rest is is an optional step that's often omitted.

But you're describing it in a way that is useless to anything but an LLM. It would have been much better if the description language had been more formalized.

Re: MCP: An (Accidentally) Universal Plugin System

#8

Post by quotemstr » Sat, Jun 28, 2025, 2:55 PM UTC

It's articles like this that tell you we're close to peak hype. There's nothing revolutionary about a text encoding plus a schema. SOAP could do this 20 years ago.

Re: MCP: An (Accidentally) Universal Plugin System

#9

Post by 0x696C6961 » Sat, Jun 28, 2025, 2:56 PM UTC

light_hue_1 wrote: post #7

kvdveer wrote: post #6

Earlier quoted context omitted.

The main difference between MCP and Rest is that MCP is self described from the very start. REST may have OpenAPI, but it is a later addon, and we haven't quite standardised on using it. The first step of exposing an MCP is describing it, for Rest is is an optional step that's often omitted.

But you're describing it in a way that is useless to anything but an LLM. It would have been much better if the description language had been more formalized.

The description includes an input and output json schema.

Re: MCP: An (Accidentally) Universal Plugin System

#10

Post by jampa » Sat, Jun 28, 2025, 2:57 PM UTC

I don't want to sound like a skeptic, but I see way more people talking about how awesome MCP is rather than people building cool things with it. Reminds me of blockchain hype.

MCP seems like a more "in-between" step until the AI models get better. I imagine in 2 years, instead of using an MCP, we will point to the tool's documentation or OpenAPI, and the AI can ingest the whole context without the middle layer.