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MCP doesn't need tools, it needs code

lucumr.pocoo.org

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Re: MCP doesn't need tools, it needs code

#31

Post by AznHisoka »

reactordev wrote: post #4
yxhuvud wrote: post #2

First rule of writing about something that can be abbreviated: First have some explanation so people have an idea of what you are talking about. Either type out what the abbreviation stands for, have an explanation or at least a link to some other page that explain what is going on. EDIT: This has since been fixed in link, so it is outdated.

MCP is Model Context Protocol, welcome to the land of the living. Make sure you turn the lights off to the cave. :) It’s pretty well known by now what MCP stands for, unless you were referring to something else…

If by cave, you mean a productive room where busy people get things done, I agree.

Re: MCP doesn't need tools, it needs code

#32

Post by nsonha »

jumploops wrote: post #20

The promise of MCP is that it “connects your models with the world”[0]. In my experience, it’s actually quite the opposite. By giving an LLM a set of tools, 30 in the Playwright case from the article, you’re essentially restricting what it can do. In this sense, MCP is more of a guardrail/sandbox for an LLM, rather than a superpower (you must choose one of these Stripe commands!). This is good for some cases, where y…

It's not guardrail, it's guidance. You don't guide a child or an intern with: "here is everything under the sun, just do things", you give them a framework, programming language, or general direction to operate within.

Re: MCP doesn't need tools, it needs code

#33

Post by cgriswald »

yxhuvud wrote: post #2

First rule of writing about something that can be abbreviated: First have some explanation so people have an idea of what you are talking about. Either type out what the abbreviation stands for, have an explanation or at least a link to some other page that explain what is going on. EDIT: This has since been fixed in link, so it is outdated.

Just so folks who want to do this know, the proper way to introduce an initialism is to use the full term on first use and put the initialism in parentheses. Thereafter just use the initialism.

Always consider your audience, but for most non-casual writing it’s a good default for a variety of reasons.

Re: MCP doesn't need tools, it needs code

#34

Post by ehnto »

jumploops wrote: post #20

The promise of MCP is that it “connects your models with the world”[0]. In my experience, it’s actually quite the opposite. By giving an LLM a set of tools, 30 in the Playwright case from the article, you’re essentially restricting what it can do. In this sense, MCP is more of a guardrail/sandbox for an LLM, rather than a superpower (you must choose one of these Stripe commands!). This is good for some cases, where y…

If you're running one of the popular coding agents, they can run commands in bash which is more or less access to the infinite space of tooling I myself use to do my job.

I even use it to troubleshoot issues with my linux laptop that in the past I would totally have done myself, but can't be bothered. Which led to the most relatable AI moment I have encountered: "This is frustrating" - Claude Code thought, after 6 tries in a row to get my bluetooth headset working.

Re: MCP doesn't need tools, it needs code

#36

Post by coverj »

faangguyindia wrote: post #16

Here is why MCP is bad, here i am trying to use MCP to build a simple node cli tool to fetch documentation from Context7: https://pastebin.com/raw/b4itvBu4 And it doesn't work even after 10 attemps. Fails and i've no idea why, meanwhile python code works without issues but i can't use that one as it conflicts with existing dependencies in aider, see: https://pastebin.com/TNpMRsb9 (working code after 5 failed attempts…

I'm interested why you aren't using the actual context7 MCP?

Re: MCP doesn't need tools, it needs code

#37

Post by laser_eagle »

xavierx wrote: post #8

Is this just code injection? It’s talking about passing Python code in that would have a Python interpreter tool. Even if you had guardrails setup that seems a little chancery, but hey this is the time of development evolution where we’re letting AI write code anyway, so why not give other people remote code execution access, because fuck it all.

[dead]

Re: MCP doesn't need tools, it needs code

#38

Post by PhilippGille »

jumploops wrote: post #20

The promise of MCP is that it “connects your models with the world”[0]. In my experience, it’s actually quite the opposite. By giving an LLM a set of tools, 30 in the Playwright case from the article, you’re essentially restricting what it can do. In this sense, MCP is more of a guardrail/sandbox for an LLM, rather than a superpower (you must choose one of these Stripe commands!). This is good for some cases, where y…

Given the security issues that come with MCP [1], I think it's a bad idea to call MCP a "guardrail/sandbox".

Also, there are MCP servers that allow running any command in your terminal, including apt install / brew install etc.

[1] https://simonwillison.net/2025/Jun/16/the-lethal-trifecta/

Re: MCP doesn't need tools, it needs code

#39

Post by laser_eagle »

s1mplicissimus wrote: post #26

I tried doing the MCP approach with about 100 tools, but the agent picks the wrong tool a lot of the time and it seems to have gotten significantly worse the more tools I added. Any ideas how to deal with this? Is it one of those unsolvable XOR-like problems maybe?

[dead]

Re: MCP doesn't need tools, it needs code

#40

Post by stanleydrew »

AznHisoka wrote: post #27
rco8786 wrote: post #24

Earlier quoted context omitted.

> when LLMs can just connect to the existing API endpoint The primary differentiator is that MCP includes endpoint discovery. You tell the LLM about the general location of the MCP tool, and it can figure out what capabilities that tool offers immediately. And when the tool updates, the LLM instantly re-learns the updated capability. The rest of it is needlessly complicated (IMO) and could just be a bog standard HTTP…

How is this different than just giving the LLM an OpenAI spec in the prompt? Does it somehow get around the huge amount of input tokens that would require?

Technically it's not really much different from just giving the LLM an OpenAPI spec.

The actual thing that's different is that an OpenAPI spec is meant to be an exhaustive list of every endpoint and every parameter you could ever use. Whereas an MCP server, as a proxy to an API, tends to offer a curated set of tools and might even compose multiple API calls into a single tool.

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