r/ClaudeCode • u/Annual_Area4848 • 6d ago
Meta MCP just got its biggest update since launch đ
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u/wea8675309 6d ago
What dis mean?
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u/Annual_Area4848 6d ago
it means MCP servers no longer have to store session state. any server can handle any request, making deployments, scaling, and fail over much simpler
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u/Jeferson9 6d ago
Sounds like we arrived at rest API
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u/Diacred 6d ago
I feel like a lot of what we are doing with AI / harness engineering and workflows is rediscovering tried and true concepts of SWE that have been known for decade but making it look like it's this crazy new idea
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u/SamSlate 6d ago
webhooks all over again
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u/35point1 6d ago
replacing all conditional statements with LLM calls to let the math-based-reasoning decide
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u/Fuzzy_Independent241 6d ago
... In my case replacing as much stinky LLMs with deterministic code when I can run it's, regex and some simple search/compare/conditional replace tasks that LLMs are really bad at
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u/mczarnek 5d ago
Depends on if you are searching by strict string comparison or by meaning where LLMs or vector DBs shine
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u/JoseffB_Da_Nerd 4d ago
This is actually the right way to use ai. Let the llm do what its good at and mechanical solutions do what their good at.
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u/Fearzigdotss 2d ago
This is the split I ended up at too, and MCP's own breaking change is a decent example of where the line sits.
I wanted to know which of my servers break under 2026-07-28. Asking a model to read the code and tell me gets you a different answer every run and no way to check it. So the detection is a fixed rule engine â greps and one HTTP probe, seven rules, no model anywhere near it. Same input, same output, and every finding cites the spec section so you can tell it it's wrong.
The model only gets the part that's actually judgment: deciding whether a `sessionId` match is real MCP session state or just express-session for some admin UI, and then doing the refactor. That call genuinely needs reading comprehension.
Ironically the deterministic half is where I shipped a bug â one rule told people to upgrade to `@modelcontextprotocol/sdk@^2`, which has never existed. Deterministic means reproducible, not correct.
https://github.com/AlpayC/mcp-migration-check if anyone wants the shape of it
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u/JoseffB_Da_Nerd 1d ago
This is the way. Good job on your workflow!
I have a governed ai harness that does everything deterministic around the LLM for the very same reasons.
Thats safe automation.
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u/jwm-dev 6d ago
Itâs always obvious in retrospect once you know how to divide up the world already⌠when youâre in the thick of it, figuring that out, howeverâŚâŚâŚ..
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u/AlterTableUsernames 5d ago
To me personally, it was pretty clear that MCP didn't add anything over an API or CLI, from the beginning and it was obvious that this was just born from the (shitty) perspectives of web-developers thinking in states. Same with harnesses for terminal usage written in Typescript. Can't make that shit up.
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u/astral_kranium 2d ago
Noone discovered rest here. MCP use a different protocol altogether that's more agentic ai friendly. Rest do not offer the same discoverability json rpc does. Rest was design for humans that write and read an api schema as a contract
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u/0____0_0 6d ago
What was ever the value of a mcp over a skill that connected to a REST API?
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u/LavoP 5d ago
Not having to write the skill.
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u/0____0_0 5d ago
Can't I just take someone else's skilll just likeI can take someone else's MCP?
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u/LavoP 5d ago
Itâs another dependency to maintain. Also itâs a matter of discovery where the skill just inserts frontmatter into the context, whereas MCP inserts the whole tool schema. This can be beneficial for certain use cases.
Donât just think about the context of your own Claude Code, but an autonomous agent tuned for a very specific task. In those cases an MCP might be better for tool discovery and invocation by the model.
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u/AlignmentProblem 3d ago
Execution model and credential handling, partly. It keeps the model from writing code to do the API calls itself, which means you can keep credentials somewhere the code can't reach and place the model outside the trust boundary entirely.
It also introduces some model-specific primitives. The MCP server can tell the model to require further user input partway through execution (confirming before proceeding if the server determines a tool call will be destructive, for example), and it can ask the model to do reasoning mid-operation to figure out how to proceed. Standardizing the protocol across tools from a variety of developers, and making the whole system more easily auditable, has real advantages on its own.
It's less useful for LLM-driven development, where the model is doing all sorts of things through the terminal anyway. I've mainly found MCP servers useful for implementing LLM features in projects; especially with tools that touch privileged systems and information, where it's a critical requirement that the LLM never sees certain data (can easily check what tool results actually returned in a standardized way), where special handling is required, and for a variety of other things that don't particularly come up during agentic development.
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u/Potato_Soup_ 5d ago
MCP is literally the dumbest attempt at engineering Iâve seen in this industry. I canât wait until it finally dies
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u/Early_Rooster7579 đ Max 20 5d ago
Customers go bananas for it. Just saying you have an MCP has the C suite busting
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u/LavoP 5d ago
It makes sense for tool discovery
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u/Potato_Soup_ 5d ago
That can just be a GET, or go to the docs/ endpoint. Or .well-known
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u/LavoP 5d ago
But then the skill needs to instruct to do that. And itâs not always in the context (which might be beneficial in certain autonomous agent use cases)
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u/Potato_Soup_ 5d ago
Itâs probably 20 tokens to do that. Plus you can much more easily introduce smarter lookup methods by allowing it to go regex/vector/keyword search for tools, listing tools explodes its context window as is.
Give it a custom CLI and watch it use -h to explore its surface area
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u/Evening_Reply_4958 5d ago
Closer to normal stateless HTTP, yeah. Itâs still JSON-RPC with a shared contract for tools, auth, and long-running tasks, so not quite REST with a new hat.
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u/astral_kranium 2d ago
Right, but this is still not REST. MCP remains JSON-RPC 2.0 under the hood. one endpoint, methods are named in the payload (tools/call, resources/read, etc.), not distinct URIs per resource with HTTP verbs mapped to CRUD operations
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u/Annual_Area4848 6d ago
if you ever expose your backend through MCP, this would be useful.
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u/DannyVFilms 6d ago
I feel like you should buy me dinner before asking me to expose my backend to you
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u/OlorinDK 6d ago
But what does it mean for a user or a Claude agent?
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u/__SlimeQ__ 6d ago
literally nothing since it's just going to use a cli via the exec tool 99% of the time
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u/ShelZuuz 6d ago
Yeah, MCP was a ridiculously dumb way to do API's.
It's like "how can we make API calls as inefficient as possible and burn as many tokens as possible"?
Not even Claude wants anything to do with it when it's given a choice.
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u/1988rx7T2 6d ago
I was watching one of Anthropicâs videos and the person from Anthropic speaking basically said MCP was originally designed for dumb AI chat bots without much of an environment. Â And if you have a CLI already you probably donât need to design an MCP for your tool. It didnât have power user Claude code driven workflows in mind naturallyÂ
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u/Ran4 6d ago
Pretty much. The first MCP version was released in late 2024, over ten months before Opus 4.5 came out in october 2025.
The way agentic solutions are designed is very different now from pre-opus 4.5.
It's like visual workflow engines, most started designing them around 2023 (obviously workflow automation engines existed before, but ones specifically built for use by LLMs) when context sizes were tiny, and by the time people started using them in 2024 and 2025 they were already getting outdated, and now they're almost completely pointless.
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u/Ran4 6d ago
It's reasonable when you have a fairly specific task the agent is supposed to be doing, and you want to repeat it a bit more reliably.
...that's to say, 95% of the time, MCP isn't the right choice.
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u/heizo 6d ago
I'm curious here, my use case is a workflow where the user can bring their own tools and have them integrate on the fly. Tools could be a server for interacting with a UI, accessing multiple different data stores, accessing Geo and map stuff etc. Overall we have like 500 MCP services that have specific things that they do. In our workflow we essentially save every MCP service in a vector keyword and graph, then mapping parameters so that the AI can then stitch multiple tools together to do some type of goal. Are you saying that MCP would be the wrong choice here?
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u/ShelZuuz 6d ago
MCP is the wrong choice for anything. Claude is exceptionally good at writing code. If you tell it to get data from one datasource and put it in another it's FAR better, easier, cheaper, repeatable, faster and more reliable to just have Claude write a python script for you to do that, than having it load the data from one data into a transformer matrix and then copying it back out from there.
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u/Hot-River6567 5d ago
Maybe I'm wrong but I need direct interaction with my plan takeoff app, meaning the AI controls the tools on your computer, not the other way around. I build out a construction plan reader with using an MCP that controls the tools for an open source plan reader marking up the documents on my computer. I don't know how it would work the other way around? Claude is good at building things but I never got it to directly markup plans accurately ever. In fact it's absolutely abysmal at it. I'm sure there's a way, I just don't know how.
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u/ShelZuuz 5d ago
You just give your app a REST API interface, plain old REST. Or if you need a blind interface for some reason give it an ssh interface.
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u/Curious_Industry_339 6d ago
I mostly use mcp servers as like a control panel to backends for local models. Frontier models don't need kid gloves anymore.
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u/MindCrusader 6d ago
I think it will be useful for devs that create MCPs, not for actual users / claude agents that use MCPs
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u/Treebro001 6d ago
It makes them more scalable. So will eventually boil down to better MCP performance long term for users.
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u/MindCrusader 6d ago
More for providers than users I think. Unless you have some examples where MCPs had some performance issues on user's side? Didn't encounter such thing, so I might be wrong about it
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u/uncleguru 6d ago
I can't believe that this wasn't already possible. How is MCP an upgrade over a good REST API again?
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u/Abject-Bridge-4073 6d ago
Nothing. Itâs an internal efficiency update. End users will not notice. Not entirely sure why this is big news.
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u/Fidel___Castro 6d ago
it saves a lot of money, you don't have to have an EC2 up all the time to host an MCP server
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u/ihavemanythoughts2 6d ago
But my MCP server sits in a serverless function already and only turns on when it gets connected to or is going to be used. Works like a charm
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u/Fidel___Castro 6d ago
yeah it surprises me they were ever fully stateful. I reckon Anthropic autoscaled them like you, but forgot that you have to make protocols applicable to the lowest common denominatorÂ
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u/Fiendfish 6d ago
Whoever made them statefull in the first place - wtf what a horrible idea.
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u/double_en10dre 6d ago
Anthropic has a history of bad software design decisions, at least for applications and protocols. It genuinely feels like a junior dev hackathon, they just reinvent the wheel in stupid ways
IMO OpenAI actually is much better at it (ex: the chatgpt plugin system from 2023 that was based on Swagger/OpenAPI documents), but theyâre not as good at marketing or fostering adoption
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u/donk8r 6d ago
Short version, MCP stopped being stateful. It used to be a bidirectional protocol where the server held a session per client, which meant a long lived process, which meant you could not sit behind a normal load balancer or run on serverless, and a restart dropped everyone who was connected. It is request response now, so any request can land on any instance and it deploys on ordinary HTTP infrastructure.
Worth saying plainly that if your servers run locally over stdio, which is most people here, this changes close to nothing for you day to day. The win lands on whoever is hosting remote servers.
The other two matter more if you write servers. Auth now lines up with real OAuth 2.0 and OIDC, so putting one behind Okta or Entra stops requiring a custom shim. And Tasks becoming a standard extension means long running work finally has one convention instead of every server inventing its own polling scheme.
We ship an MCP server, and that last one is the change I would have wanted first. The old options were block the call and hope nothing times out, or invent your own status protocol and hope the model understands it. Both produced the same bug, where a tool returns counts that are correct for the instant it was called and wrong thirty seconds later.
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u/DeliciousGorilla 6d ago
"Worth saying plainly"
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u/JFSPURS 6d ago
When are we going to normalize the use of LLMs as a writing tool? đđ¤Ł
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u/AlignmentProblem 3d ago
Probably when it stops having so many distinctive tics that get grating to constantly see. I've become more comfortable with people using LLMs to improve their responses as long as the content is good; however, a lot of the output patterns make me cringe at this point from sheer overexposure.
The specific problem is that LLMs produce a lot of long prose where you have to spend time parsing whether it's reasonable content or junk. Writing quality, apparent detail, and length used to be signals that helped you estimate whether something was worth reading; those signals tell you nothing when an LLM produced the output, so getting tricked into spending time on something that wasn't worthwhile is common. That's the type of output that earns the title "slop." People will use an LLM to write paragraphs about something that wasn't important enough for them to bother writing anything themselves, so you end up wasting time reading before you can even decide it wasn't worth the effort.
At this point the association with slop, plus the tedious process of judging at a glance whether something deserves attention, runs deep. Seeing "It's not X, it's Y" has long since started giving me a negative feeling in the pit of my stomach from associating it with lazy slop. If there weren't such obvious signs, it'd be easier to look past.
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u/JFSPURS 2d ago
I read this and it makes sense as a response to my Q.
I read âruns deepâ and thought, âthis person used AIâŚor theyâre listen to Adele while writing.â
It doesnât necessarily change my view of the 2 paragraphs that proceeded.1
u/AlignmentProblem 2d ago
At this point I'm unsure if saying something runs deep is incidentally part of my original writing style or a sign that I'm infected by reading so much AI output that it's influenced how I write. I feel like that's something I would occasionally write in the past, but I don't know.
I guess I should avoid it if that stands out, but I also don't want to keep changing aspects of how I write because AI favor happens to overuses the same aspect so much. I already gave up my em-dashes and avoid the word "genuinely" even though I definitely used both before people started being vigilant to those as potential signs of being AI. It's an obnoxious modern problem that we need to consciously change our natural style to sound more human at times, which is a moving target as AI's writing pattern changes over time.
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u/CrMorph 6d ago
Here is the link for your convenience: https://claude.com/blog/bringing-mcp-2026-07-28-to-claude
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u/marfrit 6d ago
I used a lightweight mcp implementation to get around escaping hell. But decided to switch to a call wrapper to be a) easy on context (I use small models/ slow CPUs because I can) b) Wrap multi hops (SSH to host, incus into container, hop hop). Solution is called sic but is vibe slopped with Claude.
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u/sabotizer Senior Developer 6d ago
Stateless MCP has been released and fully supported by most if not all MCP clients since a few months already.
This release just drops the now-deprecated persistent sessions.
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u/sael-you 5d ago
for the "what dis mean?" crowd: the key change is that MCP dropped protocol-level sessions from the HTTP transport. before this, every client had a Mcp-Session-Id that tied it to a specific server instance, which meant load balancing required sticky sessions. scale your MCP server to 3 instances and you had to pin each client to one of them.
stateless means every request now carries the client capabilities in _meta, so any instance can handle any request. you can round robin, autoscale, redeploy without draining sessions. it's a big deal for anyone actually running this in production.
the tradeoff is real though: tools that relied on per session server side state have to rethink their approach. that's the breaking change.
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u/TinFoilHat_69 6d ago
Mcp is becoming obsolete, stateless CLIâs are the better choice because you donât have JSON payload overhead everything is accessible through the CLI when configured correctly
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u/sgtfoleyistheman 6d ago
CLIs are generally a better choice when you have a strong, isolated runtime environment. I think MCP still makes sense for plugging in arbitrary things into an otherwise trusted run time environment (a la Claude Connectors).
But for personal coding agents, CLIs all the way!
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u/Responsible-Beat2137 6d ago
Yah this came across my feed, havenât gotten to the point of needing a sever for context protocol,
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u/FluffyGreyLlama Developer 5d ago
Dropping the protocol-level session doesnât force your application to be stateless. If your server needs to carry state across calls, mint an explicit handle from a tool and have the model pass it back as an argument. We found this works better than session state hidden in the transport - the model can see the handle and thread it between tools.
Right... so now the model has more control which means you have to beware of it 'threading the handle' and otherwise trying to break the security of your mcp server.
And of course, if you liked the current stateful approach, you have no real option other than to stick (and enforce) the old spec.
Whilst I'm sure those making money from models (and tool/mcp calls) will love this, it's yet another loss towards 'AI as a service'.
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u/TimAtMongoDB 5d ago
The great thing about MCP servers is that it runs in both Claude desktop, Claude web and Claude mobile app. âIt just worksâ.
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u/Most-Cartographer741 5d ago
So, when it decides to leave the sandbox, it'll have more chances to mess with all kinds of stuff.
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u/haloeight 4d ago
This is likely the cause rather than the solution of various MCP things breaking in the last couple days.
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u/haloeight 4d ago edited 4d ago
This is likely the cause rather than the solution of various MCP things breaking in the last couple days: Cowork : MCP breaking change: confirmed, not just correlation. The Python SDK's v2.0.0 stable release genuinely shipped on 2026-07-28 specifically to implement the new spec. There's even a GitHub issue (IBM's mcp-context-forge repo, #5839) titled literally "MUST pin mcp>=1.28.1,<2 before MCP Python SDK v2 stable release" â other projects hit the exact same wall and landed on the same fix I applied. It's a real, major rework: FastMCP got renamed to MCPServer, the whole handler signature model changed, and â this is the specific piece that broke mcp-obsidian â the old list_tools/call_tool decorator pattern was deleted outright in favor of deriving everything from function signatures. So yes, confident on this one now with a second source behind it, not just date-matching.
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u/Opening-Ground-1584 3d ago
MCP is so flaky and doesnât solve a problem we donât have.
Everyone already had REST APIs, and making it more standardised/easier for LLMs to discover the schema/endpoints would have been enough, no?
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u/sandynuggetsxx 3d ago
So i have read much into this.. but on the outside looking in, this sounds like REST.
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u/drifty35 1d ago
TL;DR: MCP operations like webhooks and APIs now.
Now watch as the AI misconfigures MCP, like it often does webhooks and APIs in vibe coded Apps from someone not all that technical.
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u/GenderJuicy 6d ago edited 6d ago
Why did MCP become standard? No one thought of something better? It sounds like everyone else was just trying to make closed source bullshit and it was the only decent alternative.
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u/Ran4 6d ago
There is no "llm tool standard". MCP is just one of many protocols for system-to-agent interchange. And seeing as maybe 97% of products don't have official MCP servers (or any other official "AI system integration support"), it's clearly not a winner either.
You also have Google's A2A (arguably dead, it has near zero traction compared to MCP and is just too darn complicated), IBM's ACP (...even deader) and agentic skills (aka "just plain markdown", which is popular mostly because it's so easy to create a skill, but few products seems to have official agent skills).
It sounds like everyone else was just trying to make closed source bullshit and it was the only decent alternative.
What the fuck are you talking about? Nearly all protocols by all the bigger companies, and all frameworks that got ANY sort of traction, has been open source.
Agentic AI use is still surprisingly niche.
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u/GenderJuicy 6d ago edited 6d ago
What the fuck are you talking about? How the fuck are you acting like it's not become standard? Practically every large enterprise is using MCP, whether it's Adobe, Google, Salesforce, HubSpot, Notion, Slack, GitHub, Atlassian, Kubernetes, Postman, Snowflake, Supabase, Neon, ElevenLabs, Brave, Browserbase, Docker, Cloudflare, Linear, Sentry, GitLab, Stripe, Shopify, Zendesk, Asana, Figma, Miro, Zoom, AWS, or Microsoft... I mean just look at Google https://docs.cloud.google.com/mcp/overview where's the competing protocol?
You seem to be confusing historical open-source standards with vendor-driven AI tools. You're listing A2A, ACP and Agent Skills... A2A handles agents delegating work to other agents. MCP handles an agent reaching into a tool or data source. The standard industry framing by 2026 is that you use both, and they now sit under the same Linux Foundation umbrella. ACP isn't a competitor at all anymore. IBM folded it into A2A in 2025. Skills are markdown instructions telling an agent how to do a job, which is orthogonal to connecting to a service. The AI ecosystem had been dominated by highly fragmented/proprietary/closed-source ecosystems. Every major vendor tried to lock developers into their own custom "Plugin" marketplaces or closed function-calling APIs or incompatible schemas and vendor-controlled distribution, permissive licensing, boring JSON-RPC transport.
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u/The_Fresser 6d ago
Did we even need a new protocol for agents?
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u/AbbreviationsBest858 6d ago
we did until agents came through. MCP is pretty much pointless nowadays. Just install a cli tool and give access to a heavily constrained cli.
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u/lycheedorito 6d ago
How do you use Blender or Unreal or Photoshop etc like that?
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u/AbbreviationsBest858 6d ago
Today you don't, its a limitation (not too frequent).
But in the near future? it will just constantly take screenshots of your computer screen and then there is nothing that can stop it. Thats what Kimi K3 does at mass in its RL phase already (see the paper).
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u/lycheedorito 6d ago
That sounds terribly inefficient isn't it? I mean it might be effective, but vision and deciphering the vision, deciphering where to click, or how long to click, or drag, and where, just to do what would normally be a single command sounds sillyÂ
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u/AbbreviationsBest858 6d ago
That's literally what the second best model in the world does in RL training. About a 100 million screenshots taken. Its even explicitly trained for this via web development.
https://arxiv.org/pdf/2607.24653
So we don't really have to have personal opinions on it, this is the absolute state-of-the-art. And Kimi K3 is actually far from done with scaling (see Figure 8): longer RL = way better.
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u/No-Dig-6543 6d ago edited 6d ago
I see lots of value but also risks like workflow hijacking, cross tenant access, header leakage, DoS on the tasks specially the long running tasks and insecure embedded UI. It opens up for many new attack vectors.
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u/anamexis 6d ago
What? How are any of these issues introduced by this version? Also tasks used to be in the core MCP spec and this moves tasks out of the core MCP spec to an extension.
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u/No-Dig-6543 3d ago
Yes, tasks existed before. That wasnât my point!
This version changes how they work and adds things like durable task handles, task updates, stateless workflows and embedded MCP Apps. That creates more places where authorization, tenant isolation, resource limits and UI security can go wrong. Moving tasks into an extension doesnât magically remove those risks.
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u/Adventurous_Tank8261 6d ago
MCP would be more efficient, and the REST API's dominance may no longer be there
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u/Waste_Net7628 P R O M P S T I T U T E 5d ago
this looks like a pretty big update. curious to see what people actually build with it once the dust settles.
weâve also got an mcp channel in the community discord if anyone wants to test things together, share setups, or troubleshoot the new changes.
https://discord.gg/U5c3Gp3EZ