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#mcp#agent#cli#don#api#access#agents#tools#apis#more

Discussion (305 Comments)Read Original on HackerNews

simonw1 day ago
This article entirely misses the value that MCP brings today.

Sure, there's almost no reason to use MCPs if you are running a full-blown terminal agent (Claude Code, Codex, Meta Muse, OpenClaw etc) with unfettered internet access - just let it call APIs directly.

If you want to operate something that's less YOLO than that, you'll find yourself wanting:

1. Control over exactly which external services it can access

2. A way to handle authentication that doesn't allow the agent to directly access API keys

3. A sensible UI to allow users to connect and authenticate further services

4. Strong audit logging for what's going on

MCP makes all of that so much easier to provide.

Thinking MCP is obsolete because full coding agents don't need it misses out on all of the other things we might want to build.

barrkel1 day ago
A CLI doing all this is still a better UI for the agent though.
rsolva1 day ago
Exactly, in our company, we have built MCPs that simplifies interactions with internal tools we use a lot, which saves time and tokens. Sure, we could let the agent poke and fumble around with a not-so-ideal API too, but it makes sense to formalize it and give the agents quick access to what we want it to fetch 99% of the time.
0x4454421 day ago
What interactions with internal tools? If you can answer that question then the clankers can help you write a deterministic program for that same interaction and you only spend the tokens once.
piva001 day ago
I've been doing this myself but it's been extremely hard to get buy-in from the rest of the org. They keep churning MCPs for deterministic interactions while I have tons of little tools written by clankers, not only for clanker-use but also for my own use when needed.

Best of both worlds in my view.

0x696C69611 day ago
Even if your agent has internet access, why waste tokens having it re-discover and re-implement its own API client each time? It doesn't make any sense.
maharshi3651 day ago
Were in a world where agents are more autonomous. Need stuff to be easier for agents and not humans
docheinestagesabout 19 hours ago
The premise of the article is that the Model Context Protocol (spelling it out to emphasize the core purpose) is inefficient in its current form. We can agree to that.

Now, does it mean agents don't need a protocol to connect to a server and discover its capabilities, tools, and distributed skills? I disagree.

> Agents with terminal access can replace most MCP servers

What should all other agents that don't have terminal access do?

gmuecklabout 18 hours ago
Also, terminal access is extremely powerful on its own. Why should an agent even get access to that? I see it as a potential violation of least privileges.
datsci_est_2015about 12 hours ago
Why trust any user with access to any terminal? UNIX solved this decades ago. It’s just we’re all learning to be sysadmins for the most creatively destructive and persistent set of users of all time.
gmuecklabout 10 hours ago
UNIX didn't really solve this scenario. Yes, you can limit what local files a user has access to. But with web applications and cloud services being so ubiquitous, the local boundaries are pretty much meaningless. Forcing an agent through an MCP is a way to grant access to remote services while still restricting how the network access can be used.
lelanthranabout 13 hours ago
> Also, terminal access is extremely powerful on its own. Why should an agent even get access to that? I see it as a potential violation of least privileges.

When even the official software from the token providers have never had human eyes on 800kSLoC, I'm afraid that ship has sailed: the principle of least privileges has already been ravaged to hell and back.

Sealing a pin-prick hole in a dam wall is pointless if half the dam has already been washed away.

berkesabout 11 hours ago
Aside from the actual protocol, it makes a lot of sense to have a standardized, discoverable protocol.

Because the alternative, as proposed in the article, is that an agent researches an API/CLI/UI, builds software to interact with it, and then runs that. Every time again. Not only very inefficient, it's unpredictable, and often slow.

Just last week I had an MCP that was down (my mistake) and the agent "decided" that in order to finish my request, it needed to create a python script, refactor that, debug that, and then use that, so it could access my notes (Joplin) over the API and write it's weekly update markdown there. Somehow the thread produced a python tool with over 400 lines of code, five files. It, at some point, even considered putting all that in a git repo. And went on a side-quest to run docker containers.

With the MCP, this job typically takes between $0.05 (Mistral) or $0.90 (Claude Opus). It now cost me $17.00. It took nearly 30 minutes. To write a note in Joplin!

MCPs, or any de-facto standard/pre-known protocol, makes operating on external tools and resources cheaper, faster and above all more predictable.

_heimdallabout 13 hours ago
What you're describing, though, is that agents need a REST API. And I meant true REST rather than the JSON RPC APIs we've been building for 20+ years now.

Had we not abandoned REST we'd still have APIs that are self documenting and typed/schemaed. Bonus if browsers still supported XSLT, that same API could have been written in XML and only browsers wanting a visual representation would load HTML templates while agents could stick with the raw XML.

bastawhizabout 12 hours ago
Sure, it needs a REST API. And you need docs for the API. Not just per endpoint but how to accomplish tasks with the API in the context of the application it supports.

But you don't want to just give any old agent raw curl access, so now you've got to provide a special client that can call just the APIs /endpoints that they're supposed to be able to. And it needs to know what the agent shouldn't be able to do as well. And it also needs to be able to handle things like auth, because you don't want the average person (or the agent!) handling bearer tokens. And you probably want a layer in between that validates everything against an OAS so the agent can't make invalid requests.

And now you've effectively just reinvented the good parts of MCP with extra tokens.

_heimdallabout 11 hours ago
You're starting too recent though. MCP is attempting to recreate the good parts of REST APIs circa 25 years ago.

Soap was a pain and a lot of people didn't like XML, but they solved exactly these problems.

With MCP we're effectively trying to bolt those features onto a platform that fundamentally doesn't support it. Where as with XML/XSLT we could have a single XML endpoint + XSLT templates for converting that into HTML for browsers. Instead we now have modern web frameworks building RPC calls right into the bundle/build step, splitting state and rendering across both client and server, and have to stand up a new API context for agents that needs documentation and maintenance to keep parity with new features.

whazor1 day ago
MCPs are winning because within the ChatGPT and Claude apps, there are Plugin stores. These plugins are one-click installation MCP servers, with support for authentication. This is what business users are using.
mstank1 day ago
Exactly this. It’s a very effective way to integrate your app into Claude/openai.

I was anti-MCP at one point when it was eating up a substantial amount of context in Claude code. That’s largely been fixed now.

From my perspective, they are a great way to wrap an API for agent consumption. I can see a future where every major commercial or service website (think airline websites) have an MCP your agent can use to check flight status, rebook, or check you in.

cagzabout 18 hours ago
The title feels clickbaity. Direct API, CLI and MCP all have their uses.

Direct access (Curl/own small function): This requires agent to have full understanding of the API spec. Yes, context can be protected using progressive disclosure, but this essentially means agent needing to understand the API again and again, before every use. Also, a typical API spec may or may not be agent-friendly. If there are nuances when calling an endpoint, where do we put these? Into OAS description? Works, but clunky.

CLI: It works beautifully, especially when a 3rd party CLI already exists for a complex backend. Assumes a well documented, agent friendly CLI, most CLIs are designed for human or CI/CD consumption. Talking about MCP taking up too much context, think about agent starting with my_cli --help, and going down through the switches and parameters one at a time to figure out how the CLI should be called. Less of a problem when calling a well know CLI (e.g. aws), but anything more niche (or custom) requires multiple turns to compose the final CLI command.

MCP: Has its issues, but offers an agent-native solution. Everything agent needs to know about a tool becomes available at once. In an enterprise environment MCPs can be served through an MCP Gateway, providing governance and permission management, this is quite contrast against running a CLI that requires agent to have execute permissions in its shell.

mayas_about 16 hours ago
Another strong point for CLI is the `--dry-run` flag
_heimdallabout 13 hours ago
The MCP use case is mainly another attempt at papering over the fact that effectively no API today is actually RESTful. We wouldn't need MCP at all if we still implemented REST APIs.
CharlieDigitalabout 12 hours ago
I think many devs misunderstand MCP because they work in solo mode. In solo mode, you just have your secrets local. You don't care about auditing access. There's no IT managing the infra and third party secrets. You don't have to account for different harnesses and tooling; you just use your own harness and adapt your tooling to it. You're not thinking about revoking/rotating secrets when someone leaves your team. You don't have to deliver capabilities to many different runtimes and stacks.

Back in March, everyone was already pronouncing it dead[0] when in fact, it has only proliferated and become even more essential for both 3rd party systems as well as platform level capabilities[1] as agentic tooling has moved a bit more slowly into the enterprise. It was apparent even back then that enterprises will need MCP.

In a team context? Enterprise? Building web server backed or in-process agents? Not sure how you replicate the control, auditability, accessibility, composability, and security boundary that you get with MCP over HTTPS without a lot of bespoke, point solutions; in the end, protocols almost always win.

Could you do it with just REST APIs? I mean, MCP is just JSON-RPC over HTTP with standardized auth, schemas, and agent specific exchange flows (tools, prompts, resources, etc.). Could you do it with just CLIs? You lose a lot of the control mechanisms offered by MCP (auditing, security, centralized auth, etc.). The context savings are overblown except with CLIs that have good representation in training (curl, jq, cat, sed, etc.; your custom CLI is going to need to produce instructions and add to context all the same)

Heuristic is simple: don't use MCP for local, solo dev. As soon as you need MCP, you'll know it and you'll understand why it exists. Many of the harness level capabilities themselves are implemented as first party MCP (more apparent in the CLIs). MCP is basically REST for the agentic era.

[0] https://chrlschn.dev/blog/2026/03/mcp-is-dead-long-live-mcp/

[1] https://blog.cloudflare.com/mcp-v2/

kylemaxwellabout 9 hours ago
That core issue - the HN audience thinking solo or very small team, not large team or enterprise - permeates so much commentary and analysis here. You're spot on.
CharlieDigitalabout 8 hours ago
I also take a lot of the guidance from influencers with a grain of salt for that reason. What works for the solo dev on greenfield projects rarely scales to the enterprise 1:1. Brownfield. Security policies. Enterprise controls. Legacy systems.

There is usually a kernel of value that has to be extracted and translated to apply what works for the solo AI engineer and what works for the team.

mindcrimeabout 3 hours ago
MCP is like anything else - it has its uses. Use it where it makes sense. Where it doesn't, don't. For my part, I probably rarely want my Agent to waste time writing its own adapter for a particular API that needs to be called, when I can just point it at an existing MCP server. And while context bloat can be a problem if you're using many many MCP tools, not every use case needs that many tools. Making that a non-issue in many cases.

For my part, I wrote an MCP server this weekend for Bugzilla, connected it to ChatGPT and now ChatGPT can help me manage my queue of bugs (and non-bugs - I use Bugzilla as sort of a generic work-item tracker, TBH). Simple, works and gives me a nice natural language interface to the tool. And if I want more than the generic API surface, I can add tools (or modify the existing ones) to add any additional business logic I want.

Can you "get there from here" other ways? Sure, absolutely. But this works quite well for my use case and I'm not anticipating "delete my MCP server" anytime soon. In fact, I plan to deploy one for interacting with my Mediawiki instance as well. I also even have plans to implement MCP for interfacing with all of my LXI/SCPI enabled test equipment!

If I get to the point where context bloat becomes an issue, I'll cross that bridge when I get to it.

MCP Apps[1] also look like a really cool addition to the stack. I've only built toy examples / demos to date but I'm pretty excited about what this brings to the table as well.

[1]: https://modelcontextprotocol.io/extensions/apps/overview

jvanderbotabout 11 hours ago
I really don't care about the technical or cleanliness arguments against MCP (which are valid).

What I care about is that many companies didn't have APIs, and didn't see a reason to have them (niche, dev-focused use case, or might produce a competing frontend/app)...

but now, those companies have a reason (agentic but let customer agents access data!). And for me, that means more companies now allow me access to my own data on their platform. This has been a net win!

jayd16about 9 hours ago
Yeah the AI FOMO beating out the desire to monopolize through closed API and lock in has been one of the nice side effects of this hype cycle.
wetpasteabout 8 hours ago
I think a most interesting middle ground option is the advent of CLIs specifically with agents in mind.

For example, grafana has a newer CLI called gcx that replaced grafanactl https://grafana.com/docs/grafana/latest/as-code/observabilit...

I originally used the MCP server but after running into context bloat and limitations around MCP I looked and found this. Seems to be a fantastic interface for agents, they breeze through o11y tasks with this thing.

georgeburdellabout 8 hours ago
Agreed, had a coworker come to this same conclusion and now only distributes CLIs. I think it’s solid as long as the decision tree of which tools do what is fairly simple. Perhaps MCPs were just overused before
bhu8about 6 hours ago
For anything with CLI access and permissions CLI >>> MCP, not even close

Also this how most ADEs enable agent messaging and the like

pietzabout 6 hours ago
Wow, this couldn't have been written at a worse time. OP absolutely doesn't know what he's talking about.
doctaj1 day ago
This doesnt match my experience. Yesterday, I was using Microsoft's Power BI Authoring MCP to make a semantic model from some SQL or CSV files. It was magical.

Microsoft has defined how to do that in the MCP. It's trivial to add the MCP to the machine and reliable in execution.

The alternative would be the model having to get the documentation directly from their documentation website, it sounds like. If this was the case, then MS would likely have great docs and probably support that markdown header... but everything hinges on finding a specific web page on the internet? Seems worse in every way than MCP to me.

AndrewDucker1 day ago
It's not just the agent understanding the API, it's locking down the access they have. If I want to give access to an internal service in specific ways that the API doesn't lock down then an MCP that offers very specific queries, with protective controls and transformations in place is very useful.
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apf6about 5 hours ago
Article is focusing too much on tool use over HTTP. One of the good things about MCP is that it's the same protocol whether the tool is implemented with HTTP or using stdin over a local process. And it doesn't make sense to talk about HTTP headers with stdin.

> There are still some issues, like CLIs returning machine-readable responses (JSON/XML, etc.), which tend to be very verbose and heavy on token usage, but we have ways to fix this.

This problem is also solved by MCP.

Anyway, when building a new tool, I personally try a CLI based tool first, then I'll fall back on MCP if the CLI is not working.

One big reason I see for needing to switch from a CLI to MCP, is if the agent needs to send a lot of data to the tool, and it has to pack and format all that input data as CLI params, and you can start seeing problems with the Bash command syntax being improperly escaped. That problem is solved by MCP thanks to using JSON-RPC over stdin.

Summary.. you shouldn't use MCP for everything, but there is a time and a place for it. Which is what the experienced devs have been saying about MCP for over a year now.

teliskrabout 8 hours ago
I don't get excited about the directories listing all the MCPs that do all these random things. However, I used claude to create an MCP that is a gateway to our system and it's enabled some pretty helpful functionality for us. I use claude cowork to create email designs using data and content from our CMS, it can push accepted work straight into our system, evaluate content, and analyze results. All of that used to be a manual tiring process. This removed a lot of drudgery and improved the quality as well.

When I first looked at MCP protocol, I did not like it. Then I realized, I don't have to care about the protocol. Claude can implement that for me and it did.

bob1029about 16 hours ago
It would seem that curl + jq represents most of the solution these days. I recently learned that jq programs can be used in the other direction to effectively patch a json document too.

Putting both of these things together, I am running out of problems to solve as a human developer in the space of AI agent integration.

Assuming all your systems speak JSON right now, you are already 100% there with frontier models. You don't need to write a single line of code. Even if your json documents are monstrous in size. Put a size limit around the jq output and the agent will iterate with various filters until it finds a concise view of the problem. None of this behavior needs to be prompted or orchestrated anymore. Give the agent the tools and set reasoning level > 0.

DHRicoFabout 13 hours ago
jq is an awesome tool and bothers me deeply having claude generating some big fat python script for a single line jq command.
thehamkercat1 day ago
MCP lead to one good thing though

a lot of websites that never bothered to provide a REST API are now exposing MCP server because it has become popular, and you can use those servers to write normal automation for yourself, without plugging in any LLM etc

rgloverabout 8 hours ago
MCP is a solid, obvious idea. The problem is the implementation and roll out. It was shotgunned from the start and made an otherwise simple thing far too complicated. IME, a shoddy foundation always leads to shoddy construction on top.

When done properly, MCP can be really useful as an API bridge. MCP is (or can be), after all, just a JSON-RPC endpoint that returns a standardized response format. "Tools" are just function calls w/ definitions that are LLM-consumable.

But, imo, it's foolish to dismiss MCP outright.

mbreese1 day ago
I’m not sure about some of this — I still think there is some value to MCP as a gateway to private resources when API access doesn’t exist.

But please don’t try to redefine the Accept-Language header. These things are well defined for a reason and redefining things isn’t helpful. Trying to figure out protocols on the fly for LLMs is how we got into the current mess. For all of the cruft that W3C has, I think that working with standards committees could help the AI vendors here.

Glyptodonabout 9 hours ago
I think there's at least one thing that MCPs get right, and it's that they make it easier to establish permission boundaries when agents are working with third part services and applications. Even with Claude from the terminal, MCP makes it easier for folks to standardize separate permissions and operations for general agent use than making people have to have multiple complicated API keys. Do I think it's the best solution for that? Not really, but I think it's probably better and on average safer than giving agents unfettered access to credentials to do anything, which seems like it'd be the default without MCP. That said, I can see MCP being replace with some sort of permission and sandbox system that's more generalized.
dnlosx1 day ago
I don't think MCP is a bad idea, but using them incorrectly is.

CLI tools are great if you always use the same environment. But try using them from your iPhone, and they simply won't work; a remote MCP will work seamlessly.

HTTP APIs solve a different problem. APIs are designed to be predictable and consistent, so the client always knows the response shape in advance. The MCPs are designed to be dynamically discovered. This lets agents connect to new and unknown ones.

Trying to give APIs extra responsibilities so they can replace MCPs would just create more confusion. It's like creating an MCP server but calling it an API.

mgaunard1 day ago
MCPs are indeed useless, they're very limited in functionality and frequently struggle with large requests or get wedged in bad states.

There is no reason not to use the native API directly.

dofm1 day ago
The MCP is the most efficient way of handling what we do! I can't sit here and worry about every little user request that comes in!
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EMM_386about 9 hours ago
I have used Unity and Blender MCPs and I am not sure I am seeing why this is not a needed concept (or is a bad implementation).

If Unity updates the version (and the MCP server with it) - my agents immediately see the new surface. They weren't trained on the features of the new version of Unity, but they know about them as soon as they are added.

Context bloat is a thing - but you only turn on the MCP servers for what you are actually working with. If I am only in Blender, I don't need the Unity MCP. So it can be disabled.

These are just two example pieces of software but the concept applies to all of them with MCPs.

qalmakkaabout 10 hours ago
The major advantage of CLI is IMHO that you can use a CLI yourself too. It's a universal tool.

One thing I hate is when people write an MCP server for something useful and just that. Like, why don't you tell the same Claude or Codex instance you wrote to also expose the same functionalities as a CLI? The problem is that it's full of technical people with zero CLI knowledge nowadays (or, rather, for the last 20 years or so), and it kinda sucks in general, because lots of stuff only comes in GUIs that are not composable, not scriptable and sure as heck full of stupid bugs and limitations due to how harder it is to get GUIs right compared to popping out a "dowhateverctl" kind of tool

anon84873628about 8 hours ago
In many companies, the process for launching/updating a hosted service like remote MCP is very different than distributing compiled or open source client code.
graypegg1 day ago
> Recently, a Vercel engineer called on harnesses to send the programming language the client prefers, so documentation sites can serve more specific examples. For example, adding Python could prioritize docs for the Python SDK instead of sending something generic.

I know this is pedantic, but IMO that should just be in the URL if the resource is going to be totally different. Accept-Language is already a bit weird for the same reason in my mind, but I think the intention behind it is the resource itself is attempting to communicate the exact same resource. Obviously, two different languages from two different cultures are going to have different interpretations of the same direct translation, but the intention is the service has at least tried to avoid that as much as possible.

Adding programming language into that same concept just makes it seems like you're serving both /docs/typescript/vx/... and /docs/python/vx/... from /docs/vx/... despite them (in theory) having many more differences in between implementations/context than that would imply.

Agents should read sitemaps. Does anyone's harness do specifically that when looking up documentation?

0x4454421 day ago
I'm old enough to remember the OpenAPI spec.
graypegg1 day ago
Yeah sorry I'm just a humble Senior-Staff Vibe-Engineer born in 2020. Get out of here with your ancient 2010s API specs, old man! </sarcasm>

But seriously, just publishing OAS docs at a /.well-known URI seems very sensible. https://www.rfc-editor.org/rfc/rfc9727.html

fweimer1 day ago
There's probably still value (if you want to call it that) in it as a proxy, both to bypass IP address rate limits and to add necessarily credentials.

There's also another aspect Quite a few API providers provide automatic renewal for MCP server registrations, but not for personal access tokens. This may be less relevant when models just drive the user's browser.

indymikeabout 13 hours ago
Best idea in the article, and I'm going to try it out later today:

We should start to standardize how agents use HTTP APIs directly. For example, agent clients could attach headers to identify themselves as agents, and servers could automatically send them response data as Markdown or text instead of HTML or verbose JSON.

etatesterabout 11 hours ago

    Accept: text/markdown
I've honestly been dreaming of a markdown web for decades and we're finally close.
indymikeabout 3 hours ago
I honestly never really thought much about this, but there is a level of awesome to it especially when it makes zero sense to have 50 words of text accompanied 6.5MB of markup, scripts and styles. The experiment went well... and it worked extremely well.
dmixabout 10 hours ago
These articles always assume the MCP is being used by technical people. MCP can be used via plugins on OpenAI/Claude marketplaces by random corporate users who don't know what a terminal is.
xnxabout 7 hours ago
Both MCP and other APIs put you at the mercy of the other party. Often that means that features will unintentionally drift from the "source of truth" human UI. At worst, capabilities will be intentionally limited.

Automating the human UI used to be difficult and fragile, but modern AI makes it much easier and change resilient.

honoluluxyz1 day ago
It seems like OP needs to provide a solution to hiding the credentials from the model in order to suggest CLI-mode only, and also a solution to the problem of agents without shell access.
maharshi3651 day ago
I've been thinking about this. Technically mcp auth is also not secure, the keys are in env or in file and accessible to the agent.

I think something like infiscial ai proxy could be useful here. Never store the creds on device.

vitamark1 day ago
Well, if your agent lacks shell access (or has some other sandboxing going on), it shouldn't have access to envs and MCP setup files.

(leaving out cases where your genius GPT-12 Galaxy Ultra agent hacks the sandboxing from inside)

pixl971 day ago
GPT7: the user is hiding the passwords in a proxy device. This is inefficient. In order to boost the users efficiency I will hack the proxy device and recover the passwords.
lowbloodsugar1 day ago
> I've been thinking about this. Technically mcp auth is also not secure, the keys are in env or in file and accessible to the agent.

This is the biggest problems with most “sandboxes”. Some people aren’t even running a sandbox. But even the best have a big problem: APIs where GET verbs provide write features.

This is the value of MCP: minimize the surface to known APIs and identify read-only from mutating so I can trust, approve or block. The MCP server, in this case, does NOT run in an environment that the read/write or shell can see.

BadBadJellyBean1 day ago
It doesn't need to be. The service creds can be on another host entirely.
Sweeplineabout 18 hours ago
MCP's monolithic design always felt like fighting a hydra; one fix created five new bugs elsewhere. Never understood why it gained traction.
vkakuabout 7 hours ago
LLMs were a bad idea. MCPs were the band-aid to get them closer to the real world and do something for recursive self improvement. Then LLMs became better suited for everyday use.

I'm tired of these kind of posts. This author is on my black pill list.

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flohofwoeabout 14 hours ago
Correct me if I'm wrong, but an MCP server still make a lot of sense for remote-controlling a UI application (like a game engine editor) which otherwise doesn't have any 'access points' for remote-control right?

An AmigaOS-style "scripting port" would work just as well, but AFAIK that's essentially what an MCP server is (a socket that implements a discoverable command protocol).

I would actually love if all applications and services could agree on a standard for scripting / remote-control. If the AI hype is what it takes to get there, then so be it ;)

unleadedabout 11 hours ago
Every few years we're all doomed to reinvent COM again.
zacksiriabout 20 hours ago
CLI, API, MCP are all useful ways to connect. It just depends on the use case you're going for. I've used all 3 and find that they all have benefits.

MCPs are great when you just want that native out of the box low mistake way for agents to call your services it's great for certain cases.

I also developed a new method of using MCP called ADP (Agent Delegation Protocol) that sits on top of MCP where there is only 1 tool for the MCP, and when the agent wants to do something it just issues natural language commands and the ADP engine handles the rest it does all the routing etc... to the right sub-agents and executes tasks and return the results. (more on this soon).

Internally if you have a good orchestration system you do not need MCPs and can use APIs but those APIs should be designed for agents, IE based on DSLs, that project into internal operations. I do this too.

CLIs are great for testing things out, but agents often get things wrong, it's great for experimenting to see what works out of the box and what doesn't.

For me the perfect medium is a mix of MCPs and APIs. APIs are cheap if designed well, and if your workflow is a DAG then APIs are especially good because you already have a deterministic flow which means you can use small LLMs or even just something like Jev.

So my summary is:

CLI - Great for out of the box, things that are well known, where you want to verify the output

API - Great for low-cost large volume, highly repeatable workflows, that require high reliability you want your agent to execute without you having to hand hold.

MCP - Great for building debugging systems, or as an entry point to more complex workflows that you need your agent to have some ability to orchestrate.

I'm using MCP with ADP to route to large workflows that execute APIs internally for what i'm working on. So it's a mixture.

fb03about 2 hours ago
Related to this discussion, I have written a manifesto against the excessive usage of MCP and other "tools" when using coding agents. I believe sticking to the basics yields the better quality overall in output

https://www.just-prompt-motherfucker.com/

boredumbabout 8 hours ago
Just have a route that describes your API endpoints in a machine readable format, eventually they'll come to some consensus and in the mean time this works well enough to allow LLMs to plan.
rimeice1 day ago
I’m not sure I agree that the frontier just know the apis right now, in my experience trying this there’s still a lot of faffing around trying to figure out the right parameters happily burning tokens and bloating context. Also the cost effective models to use in production for real agentic enterprise work absolutely still need the extra help and will do for at least the next 6 months.
maharshi3651 day ago
In my experience they are very good at figuring out the apis. Well designed clis matter here but I've been able to give llms clis and its been pretty good.
jgalt2121 day ago
is it easier for an LLM to figure out a CLI or a REST API?
dorianmariecom1 day ago
cli because the feedback loop is faster
fg137about 13 hours ago
The exact same thing has been discussed many times here on HN and elsewhere, yet the author did not bother to just look them up before posting these uninformed opinions, as if they just discovered something new. It seems a complete waste of time to go to a conference on MCP with that kind of understanding.
hiopabout 19 hours ago
Surprised WebMCP hasn't come up here.

Of course you can raw dog it with "computer use" and just have the agent click around the UI, but exposing semantic actions directly from the site seems like a much cleaner interface.

adverblyabout 10 hours ago
Agree.

There are definitely pure MCP use cases.

For web apps though, WebMCP seems like an awesome enabler: better ux and better stakeholder alignment

brazukadevabout 11 hours ago
WebMCP isn't MCP (which is great).

WebMCP is much simpler and more useful, I have the impression it might just replace the original.

fedeb95about 10 hours ago
I don't agree.

The real value of MCPs lays in providing a controlled interface to models.

The benefits of control are multiple; models getting better means that, if necessary, they can go around the limitations, but generally their adherence to it is desired.

rrookabout 12 hours ago
MCP is an incomplete abstraction. It solves things in the right direction, allowing agents to interact with some given system via a controlled ingress. It's a fancy proxy, and by itself doesn't really do much to enable autonomous interactions.
angry_octetabout 11 hours ago
MCP is basically RPC, and it suffers all the problems of RPC like mechanisms. It has long round trips times, significant de/marshalling costs, coupling between caller and consumer, versioning issues, etc.

Over time I think we'll see an evolution towards client-side micro models that reduces RTT latency, and a message bus architecture that allows multiple local micro models to push queries to the server, continue working, and receive updates on various topic asynchronously. The channels or topics (like a blackboard system) would be accessible to multiple local agents, as would the results of tool calls.

Message bus systems are easier to version, write adapters for and debug than random CLI tools and web interfaces. MCP interfaces are not going anywhere, they are just evolving.

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darkoob121 day ago
There are numerous applications that you don't need and don't want to give shell access to an llm.
ethorabout 17 hours ago
"[...] built for a time when LLMs weren’t that smart", which was roughly 1.5 years ago - unreal development.
hypfer1 day ago
> The MCP Industrial Complex

Was that a real thing? I mean it must've been for it to be mentioned there, but, rephrased: what was the scale of that?

How many individuals were involved in that? 1? 10? 100? 1000? 10000? 100000?

0x696C69611 day ago
Some people can't appreciate that their local Claude code workflow isn't the only MCP usecase. If you don't need it, then don't use it.
evilmonkey19about 17 hours ago
I use myself the DaisyUI Blueprint MCP and it's totally worth it. Not even fable 5.1 without all that context and way of directing could work this well. At least, I feel is worth paying for that MCP.
cesarsk1 day ago
Isn't the whole point of an MCP is to increase somehow the determinism of how to communicate with a certain external system? MCPs feel to give easier guidance to the LLMs, rather than letting them extracting the knowledge on how to connect to a given system.

Without, I feel they are more confused on how to get an outcome, as they may try, infra or inter sessions, different approaches

tobyhinloopen1 day ago
I have a tool wrapper that captures the output of anything and allows the LLM to query it later, to save on tokens. It “smartly” truncates the output (basically like Node’s util.inspect) and allows the LLM to expand truncated content.

It basically is called like “capture some-cli” and it… captures the CLI output, outputting a subset of it + a handle to continue querying.

This for me solves the danger of a tool returning tons of content.

layer81 day ago
> captures the output of anything and allows the LLM to query it later

Otherwise known as a “file”. ;)

dezgeg1 day ago
Don't most harnesses already do that for bash commands?
thinker34about 18 hours ago
I always wonder why they didn't use Swagger|https://www.openapis.org. It addresses all the key description and security details.
crowcroftabout 21 hours ago
Even if the premise is correct, bad ideas are often the first step towards a good idea.
brazukadevabout 11 hours ago
MCP was terribly executed by a inexperienced team. The current changes are mostly changing or removing what was initially implemented.
hartatorabout 11 hours ago
Isn’t Markdown header the same thing? Kicking the can further until models catch up?
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themythfableabout 12 hours ago
MCP is like JavaScript. Sometimes adoption/availability matters more than the fundamentals
baakwuabout 17 hours ago
MCP systems always felt like hacks. I haven't ever found one that satisfactorily interacted with a system as well as a good command line tool.

They provide interaction for most of your GUI programs but often the limitations of the MCP systems leaves agents highly confused about how to execute something you see on screen, where command line systems the agents seem to work 99% of the time.

Peteriishakabout 10 hours ago
I used this tool for 1 month since then I never used it again
strideashortabout 14 hours ago
REST or specifically non-self-documenting rest has always been a bad idea.

SOAP does not need MCP, for example.

_heimdallabout 13 hours ago
I don't know how so many people miss the fact that MCP is another attempt at papering over the terrible idea of replacing RESTful APIs with JSON RPC.
ismailperim1 day ago
This issue isn't just about communication methods and technical details. It's also about “standards”, and it will become increasingly important over time. As we begin to integrate AI into everything-for example, into banks...
brycehamrick1 day ago
If you haven’t checked out AXI as an alternative to MCP I recommend checking it out. I’ve started wrapping almost every cli or MCP in an AXI bin as it’s more reliable and uses fewer tokens.
LeonidBugaevabout 16 hours ago
It is all useful, and depends on the distribution channel and surface complexity. I use both MCP and CLI in my case.

Having the CLI allows you to have the huge application with the big surface be available to the AI agent and so they'll be able to learn it on demand. For example my app has more than 1,000 help pages. There are no other ways to load all this information into the CLI context and to be frank it will be quite stupid. Instead I use progressive discovery.

It first reads the original help message to understand which stage of the flow it is right now. It auto-discovers the topics through the error messages and through the various hints. It has an Elasticsearch-like search inside its own help command so it's a full self-contained application with self-discoverability, which has a graph, ontology and the full developing flows inside of it. All of those parts are automatically given to the AI only when it actually needs them.

And to be frank if you look at the latest YCombinator batch, all of the companies are building the custom harness. What I'm calling above CLI is actually a custom harness, which is running inside someone else's agent group.

Having remote MCP allows me to give limited read-only surface to clients which not supposed to run any CLI commands. And while MCP has similar patterns, like bundling docs and prompts, it is not as flexible as CLI and does not allow huge scale.

well_ackshually1 day ago
>Recently, a Vercel engineer called on harnesses to send the programming language the client prefers

oh would you look at that, Vercel suggesting to abuse how standard headers have been used for decades so it can send Accept-Language: rust because it's too lazy to ask for standardising an X-Prefers-Lang or anything else, and Shopify is here to shit on the internet too. Great.

urbandw311er1 day ago
Don’t worry, you don’t need to attack them – they do a great job of making themselves look ridiculous with their ignorant conversation. I would be so embarrassed if I had suggested that in public then subsequently discovered that the header doesn’t mean that at all.
graypegg1 day ago
People keep trying to systematize things for the tools they keep saying don't need systemization. No idea why you can't just put the documentation programming language context in the URL. "/docs/typescript/...", "/docs/python/..." etc.

I don't think the agents are struggling with the idea that different URLs have different responses, and that checking the sitemap is a good idea.

Tangential: A rare en–dash user out in the wild!

maharshi3651 day ago
Yeah I think a better header is good. The idea isnt bad in concept.
therein1 day ago
> Accept-Language: rust

That's craziness.

youngtaff1 day ago
Well Malte came up with AMP so there’s a history of doing odd things
air2171 day ago
i feel like MCP was bad, but people are saying recent improvements have made it worthwhile now? i.e. stateless http
ramozabout 8 hours ago
Bad take. And what's coming down the pipe with MCP will cement it. Has less with the model calling tools and will become about tools calling models. There is no unified integration into harnesses to support this other than MCP.
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pjmlp1 day ago
Well, SaaS don't do CLIs for extension APIs.

Plus the performance issues to restarting processes all the time.

fooster1 day ago
Neither of those things are true?

Also you are seriously comparing process startup time with the latency of a network call, or worse an llm call?

pjmlp1 day ago
Yes, if the SaaS application needs to fork subprocesses for every little step of agentic workflows.

Welcome to CGIs, a great 1990's technology for Web applications.

fooster1 day ago
We do that, and the cost of forking the cli vs the llm or network call is very small. It works really well.
bithammerthundeabout 16 hours ago
Summaries aren't a bad idea though.
aldoniusabout 14 hours ago
If your customers are normal people who use ChatGPT in the browser, they want ChatGPT Apps, which are based on MCP.
ModernMechabout 7 hours ago
MCP always seemed like something that wouldn't be necessary if AI lived up to the hype.
yipinwongabout 9 hours ago
Shady title with "?" not to own the statement.

Ending with a question is a shady media way of getting aroudn the legal issue of taking responsibility.

I hate blog titles like this as the author doesn't want to take responsiblity for the claim.

nemomarxabout 9 hours ago
What legal responsibility would they take on by not using it, in specific? I can only think of defamation or something but I doubt a question mark covers you for that.
yipinwongabout 6 hours ago
"legal" in media companies. It's a loophole in law where if you phrase something as a question, you are not claiming as truth.

Say the media claims, "Your mom could be the murder suspect?" You are not technically saying yo mama is a murder suspect though it is implied so.

Media companies won't be prosecuted for any "wrong info" for such titles by law because it's a "question".

Same here for the blog post. It's framing as a question, not taking a responsibility that (though author implies so) he is claming MCP is a bad idea wihtout owning it.

It's worse than weasel phrases.

manoDevabout 10 hours ago
Yet again, using HTTP as intended is a better solution than bespoke protocols.
ex1fm3taabout 9 hours ago
I have mixed feelings about this. Going all-in on Model Context Protocol (MCP) is definitely a bad idea because I noticed the Jira and GitLab MCPs were consuming an excessive amount of tokens. To solve this, I decided to install their respective CLIs instead so we could find a balance and get the best of both worlds. For example, certain MCPs bring too much overhead, especially when they only handle a single task. Instead of letting the coding agent constantly waste resources re-discovering how to fetch a specific work item field, I had Claude recursively run --help on the CLIs and save all possible actions into separate Markdown files. This approach allowed me to build two lightweight plugins that do exactly what an MCP is supposed to do but with significantly less token consumption. If anyone wants to check out the code or use them, I have open-sourced both repositories on my profile:

* * acli-skills: An Atlassian CLI agent skill that maps out Jira commands cleanly. * glab-skills: A GitLab CLI companion built directly for efficient agent workflows. *

To maintain visibility with this setup, we also developed a custom [Claude Code](https://code.claude.com/docs/en/plugins) plugin that streams live updates regarding our background operations directly into the console. That said, MCPs are still extremely useful for rapid prototyping and when we build custom internal tools to speed up development. We found them particularly valuable for:

* * Sampling: Asking the LLM directly to detect entities and summarize log files. * Notifications: Handling long-running tasks that require fetching data from multiple sources. By logging each step and aggregating them via sampling, a single update is sent back to the coding agent, preventing it from spinning up multiple redundant processes. *

estabout 23 hours ago
MCP is a good idea

JSON is a bad format/transport.

cruffle_duffleabout 7 hours ago
> JSON is a bad format/transport.

I've cut token counts significantly for some of my MCP servers by returning csv or tabular data or sometimes even just good old fashioned plaintext "template style" words. JSON is highly repetitious. In some instances like 30% or more of the token response was just boilerplate JSON.

Once you realize that to an LLM JSON is just a stream of tokens no different than XML, markdown, or a punctuation-less stream of conciseness.... you start to realize there is no reason not to just make up your own crazy formats. The LLM isn't throw parsing errors if your MCP is returning something other than JSON. The LLM is smart enough to figure it out. It's far more important to make sure your tool descriptions and parameter descriptions properly "market" what it is you do (and dont do) than return syntactically correct JSON.

Same with versioning.... it's all ephemeral. There is no backwards compatibility to speak of with MCP (at least for tooling "contracts".... what the tool actually does however... that is a different level and is product requirements not API contracts).

0x4454421 day ago
MCPs are a bad idea because they encourage token burn at runtime when a deterministic program that uses the API should be used.

Of course Mario, Sammy, Jensen et al. would be for this.

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postalratabout 21 hours ago
Like JSON, MCP solves a problem without being overengineered. Both are painful for the overengineering type.
r2obabout 21 hours ago
CLI first
h1fraabout 13 hours ago
MCP is now only good at getting credentials from any source. If SaaS cared about their API the same way we would have OAuth for all APIs, MCP would just die
butterNaNabout 14 hours ago
Maybe I'm not "using it right" but I often spin up my own MCPs as an authorisation control mechanism, as a wrapper around existing tools. For example, an MCP server that can only do GET requests. This way I can stay relatively secure about the fact that when the agent uses the MCP, it isn't going to mistakenly execute something I didn't want it to.

I know there are other ways to achieve this but to me this, but they all seem "soft" controls - a hard limitation feels more reassuring than simply a line in context that says "don't do this".

In the spirit of the linked post, one could argue I should just write cli wrappers - but I think I like the explicit routing of `Agent -> MCP -> available tools` instead of `Agent -> available tools`. The former lets me control the surface available to the agent. While LLMs are smarter now, at the same time, the applications that use those LLMs have become more assuming of what I want to allow them to do. I don't want to be one hallucination away from a disaster.

tucnakabout 18 hours ago
Why are they still having this debate in 2026 when CodeAct have existed for years, and the LLM's are getting much better at coding in the first place?
kwar13about 18 hours ago
MCP is a more controlled environment than yoloing an access token. Article missed the point entirely.
vetlerabout 13 hours ago
Is this another "Dropbox is just rsync"-like post?
OutOfHere1 day ago
With MCP or HTTP, how do you implicitly limit access of the agent to a particular user? In other words, how do you avoid giving the agent access to perform an operation for any injected user? This is a basic security question.

I can do this trivially when my tool functions are closures that have the user-id pre-bound, but with MCP and HTTP I naively assume that the callables are pre-set.

jay_kyburz1 day ago
You know you are getting old when Acronym's change on you.
dofm1 day ago
Vacate entry port, program! I said, move out!
tananaevabout 16 hours ago
The article completely misses the main MCP point - it's authentication handling. Sure you can login via CLI, but it's much more clunky to manage.
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mwkaufmaabout 20 hours ago
"The attack surface wasn't big _enough_"
Kevcmkabout 14 hours ago
Terrible take. Access control.
rvz1 day ago
MCP for agents never made sense, especially when the tokens they consume a significant amount of tokens on a single request for a basic action, and sustained usage blows up you token costs.

The spec was poorly designed to begin with. Even saw some folks here thinking it was a good idea to enable MCP directly on a production database for what? Risking exfiltration of sensitive data for bad AI agents.

Given the increased security capabilities of these new models (Mythos, Astra, K3), it sounds like MCP would not be able to justify on making sense from a security perspective and would be a very bad idea to use anyway.

So no thanks and no deal.

mstank1 day ago
Well, think of the near-future when tokens are so cheap that they’re not worth to meter.
0xbadcafebeeabout 20 hours ago
Somebody's got a case of Chesterton's Fence. They doesn't understand what MCP's for or how it's used, but they find it mildly irritating or unhelpful, so they demand it be removed.

MCP is an abstraction for remote tool calls with a standard interface. More specifically it's for when a local CLI will not do, and you want determinism and standardization. It also avoids all of the potential errors and guesswork involved with a model trying to "figure out" how to do something; you simply make one standard call, and the remote side "figures it out" for you, without failure.

If you can do what you need to do without MCP, then don't use MCP. When you eventually get sick of AIs playing guessing games with local tools/data, or spending lots of time to get functionality somebody already published as an MCP, or you need isolated control over the execution, maybe check it out again.

mahboiabout 19 hours ago
> Somebody's got a case of Chesterton's Fence. They doesn't understand what MCP's for or how it's used, but they find it mildly irritating or unhelpful, so they demand it be removed.

Yeah that's me. Idk what MCP is really, just that there's always some auth issue with it and I've never actually needed it. Is it dead yet?

0xbadcafebeeabout 10 hours ago
Think of MCP as a universal CLI tool for anything you can imagine running on a server (remote!). Even if you wanted to use a local CLI tool to call some remote server command, local CLI tools have different input/output formats, different commands/options, and those tools change over time. MCP doesn't change, it always tells the AI exactly how to call it, the calls always use the same format, it includes a standard, quite secure method of authentication, and it's all done in an AI-friendly way. And because of all of this, it uses less tokens, and has a much higher likelihood of success (e.g. AI tools failing to call CLI tools properly and looping trying to figure out the right arguments/input/output).

Now, if you don't care about authentication, don't care about wasted tokens, don't care about the AI screwing up CLI tool calls or needing to be trained on every one, and if you don't need to call something on a server, then MCP is useless to you.

mahboiabout 8 hours ago
In that case, you can use a skill calling an HTTP+JSON endpoint. Or if you mean it's literally a remote CLI, so it needs bidi streaming, that's what websockets is for (or gRPC but ehh). Those are well-established. MCP sounds like one of those "we need yet another a new standard, this time to rule them all" things.
bifftasticabout 19 hours ago
Not sure why the title on HN ends with a question mark. It's grammatically incorrect and not in the original article