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tptacek parent
I do think the big story here is how hyperfocused and path-dependent people got on MCP, when the actually-interesting thing is simply "tool calls". Tool calls are incredibly interesting and useful. MCP is just one means to that end, and not one of the better ones.
simonw
I think MCP's huge adoption was mainly due to its timing.

Tool calling was a thing before MCP, but the models weren't very good at it. MCP almost exactly coincided with the models getting good enough at tool calling for it to be interesting.

So yeah, I agree - most of the MCP excitement was people learning that LLMs can call tools to interact with other systems.

aabhay
One thing about MCP that some people forget is that the models are post trained on MCP-based rollouts. I think people imagine that MCP was something people discovered about models but it’s deeper than that — models are explicitly trained to be able to interpret various and unseen kinds of MCP system prompts.

The exact same is true of these Claude Skills. Technically this is “just a system prompt and some tools”, but it’s actually about LLM labs intentionally encoding specific frameworks of action into the models.

simonw
A source I trust told me that Anthropic's models haven't yet been deliberately trained to know about skills.
kobalsky
MCP servers are basically a tool call registries, how could it be worse than a regular tool call?
behnamoh
an MCP server can run code outside of the domain of tools that it supports, tool call can't
TeMPOraL
Tools are literally function calls with extra steps. MCPs are interpreters of those function calls.

Same stuff, different name - only thing that's changed is that Anthropic got people to agree on RPC protocol.

It's not like it's a new idea, either. MCP isn't much different from SOAP or DCOM - but it works where the older approaches didn't, because LLMs are able to understand API definitions and natural-language documentation, and then map between those APIs (and user input) on the fly.

brazukadev
> MCPs are interpreters of those function calls.

No, tool calls are just one of many MCP parts. People thinking MCP = SOAP or DCOM or JSON-RPC or OpenAPI didn't stop 20 minutes to read and understand MCP.

Tool calls is 20% of MCP, at maximum. And a good amount of it is dynamically generating the tool list exposed to LLMs. But lots of people here think MCP === give the model 50 tools to choose from

simonw
"Tool calls is 20% of MCP, at maximum"

What else is there? I know about resources and prompts but I've seen almost no evidence of people actually using them, as far as I can tell tools are 90% of the usage of MCP, if not more.

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didibus
> Tool calls are incredibly interesting and useful. MCP is just one means to that end, and not one of the better ones.

It's nice to have an open standard though. In that sense it's pretty awesome.

But MCP isn't just tools, you can expose prompt templates and context resources as well.

All the skills that don't have an added dependency on a local script could just be an MCP resource.

tptacek OP
You don't need MCP for prompt templates and context resources. Those are both just forms of prompting.
didibus
I'm not sure what you mean? LLMs can only be interacted with using prompting. Even the tool call response from OpenAPI is them just wrapping the prompt on their side of the API with another prompt.

So everything else is just adding behavior around it.

MCP is a way to add behavior around LLM prompting for user convenience.

kasey_junk
MCP seems valuable in that it teaches the llm about oauth. So you can do server based tool calls.

Before that you had to install each cli you wanted and it would invariably be doing some auth thing under the covers.

Took calling was certainly the big llm advantage but “hey tools should probably auth correctly” is pretty valuable.

3abiton
I would argue MCP is technically a "tool calling" approach, albeit more specific.
tptacek OP
It is, it's just a very specific approach, and it's simultaneously a bit underspecified and a bit too prescriptive.
manojlds
To clarify, MCP was also a Anthropic innovation.
behnamoh
it's not much of an innovation though. it's just a fancy (and unsafe) way of keeping a registry of tools.
speedgoose
Why unsafe?
smrtinsert
Im already doing "skills" via 1 mcp tool calling a db and its works fine

Not sure what skills adds here other than more meat for influencers to 10x their 10xed agent workflows. 100x productivity what a time to be alive

jgalt212
Other than, presumably Skills, what other techniques are better than MCP?

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