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Posted by ejholmes 13 hours ago

When does MCP make sense vs CLI?(ejholmes.github.io)
330 points | 211 commentspage 7
jngiam1 9 hours ago|
I think if you want background agents with sandboxes and well scoped permissions, you want MCP to be your data protocol and security layer.

If you’re vibing and doing the open claw thing without any security concerns; then you’re absolutely right.

ryanthedev 5 hours ago||
CLIs are dead. Long live the skill. Which is a wrapper around the CLI! Haha.
entrustai 9 hours ago||
The CLI vs MCP debate is about input ergonomics — how the agent invokes tools. Both sides are arguing about the left side of the pipeline.

The harder unsolved problem is the right side: what happens to the output before it becomes consequential action. Neither a CLI nor an MCP server tells you whether the text the agent just generated is compliant, scoped, or admissible. That enforcement problem exists regardless of which invocation pattern you prefer.

The best CLI in the world doesn't help you when the agent produces a clinical summary that omits a contraindication or a financial disclosure that drifts outside regulatory bounds. That's a different layer entirely — and it's mostly being ignored while everyone argues about transport protocols.

deadf00d 8 hours ago||
IMO the biggest issue with CLIs for agents is to know when the agent is allowed to type. When is the command fully proceed, and next tokens can now be generated.
brumar 11 hours ago||
For personnal agents like claude code, clis are awesome.

In web/cloud based environment, giving a cli to the agent is not easy. Codemode comes to mind but often the tool is externalized anyway so mcp comes handy. Standardisation of auth makes sense in these environments too.

the_mitsuhiko 12 hours ago||
> OpenClaw doesn’t support it. Pi doesn’t support it.

It's maybe not optimal to conclude anything from these two. The Vienna school of AI agents focuses on self extending agents and that's not really compatible with MCP. There are lots of other approaches where MCP is very entrenched and probably will stick around.

orange_joe 13 hours ago||
This doesn't really pay attention to token costs. If I'm making a series of statically dependent calls I want to avoid blowing up the context with information on the intermediary states. Also, I don't really want to send my users skill.md files on how to do X,Y & Z.
krzyk 12 hours ago||
Why? MCP and CLI is similar here.

You need agent to find MCP and what it can be used for (context), similarly you can write what CLI use for e.g. jira.

Rest is up to agent, it needs to list what it can do in MCP, similarly CLI with proper help text will list that.

Regarding context those tools are exactly the same.

lmeyerov 12 hours ago||
This feels right in theory and wrong in practice

When measuring speed running blue team CTFs ("Breaking BOTS" talk at Chaos Congress), I saw about a ~2x difference in speed (~= tokens) for a database usage between curl (~skills) vs mcp (~python). In theory you can rewrite the mcp into the skill as .md/.py, but at that point ... .

Also I think some people are talking past one another in these discussions. The skill format is a folder that supports dropping in code files, so much of what MCP does can be copy-pasted into that. However, many people discussing skills mean markdown-only and letting the LLM do the rest, which would require a fancy bootstrapping period to make as smooth as the code version. I'd agree that skills, when a folder coming with code, does feel like largely obviating MCPs for solo use cases, until you consider remote MCPs & OAuth, which seem unaddressed and core in practice for wider use.

phpnode 12 hours ago||
the article only makes sense if you think that only developers use AI tools, and that the discovery / setup problem doesn't matter
trollbridge 12 hours ago||
But that's the current primary use case for AI. We aren't anywhere close to being able to sanitise input from hostile third parties enough to just let people start inputting prompts to my own system.
phpnode 12 hours ago||
there's a whole world of AI tools out there that don't focus on developers. These tools often need to interact with external services in one way or another, and MCP gives those less technical users an easy way to connect e.g. Notion or Linear in a couple of clicks, with auth taken care of automatically. CLIs are never replacing that use case.
medi8r 8 hours ago||
To be fair to MCP it came out 150 years ago, in November 2024. Agents were running on steam and coal then with Sam Altman shovelling the furnace.
_pdp_ 10 hours ago||
https://github.com/mcpshim/mcpshim - converts MCPs to CLI - best of both worlds
mrshu 9 hours ago|
It really seems the primary benefit of MCP servers was to force companies to establish some externally exposed APIs if/when they did not have them.
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