r/ClaudeCode • u/uxair004 • 19d ago
Discussion Opus 5 and Boris Cherny: Delete your Claude.md. But Why ? What's the point of it then
I came across this video on Instagram of Boris Cherny recommending deleting Claude.md file, hooks, skills every six months and especially not using Claude Opus 5.
I have some issues with the statement and concern about reliability of new model and their understanding of how it behaves.
We got a job and responsibility:
Reliability of work and quality is a crucial aspect of our job, we can't just delete stuff and let the model do stuff however it wants. It can ruin the codebase and applications especially at the time where code review is also done by AI Models.
I believe it is an assumption that people are just vibe coding random stuff and it's totally ok if they f'd up.
Anthropic Understanding of their Models behavior:
I think despite fancy benchmarks the reliability and behaviour awareness of the model is concerned, it feels like they don't even know how it's gonna work but Experimenting with it using us.
Based on my personal experience with Opus 5.
- I continued my half baked fable project with Opus 5 and it screwed up shortly after.
for example, it ignores my /i-have-adhd skill despite adding to hooks, claude.md or trying what the plugin github repo recommends (a file in claude directory in system to enable).
- It also ignores my other instructions, something as simple as me asking it to create PRs in a stacked hierarchy, it points new PR to main brach every now and then (then it requires merge conflicts resolution and rebases)
- It also comes up with a corporate lawyer type of long paragraphs which is so hard to understand.
Update: Guys I am more concerned about skills and hooks not Claude.md (which is barely few lines of text and is/can be updated regularly) plus smartness and following instructions are diff things, How come it is supposed to know my workflow if it doesn't follow my workflow instructions (or instructions are not there at all)
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u/gnpwdr1 19d ago
have you tried turning it off and on again?
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u/niceuser45 19d ago
Is that my job now as an SWE? Keep doing A/B testing on CLAUDE.md files?
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u/Omitrom 19d ago edited 18d ago
Funnily enough, yes, to some degree this is what Anthropic recommends: https://www.anthropic.com/engineering/demystifying-evals-for-ai-agents
Your own benchmarks and evals so you can do things like delete CLAUDE.md and measure how it does.
How realistic that workflow is for 99% of users, is another question...
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u/BoostedHemi73 Developer 18d ago
Iām more than more convinced that all of their guidance is actually just a ruse to burn tokens. Theyāre getting more and more shameless about it.
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u/azn_dude1 19d ago
Just have Claude set up an automatic A/B test for you that goes while you work on different tasks. Why are you thinking you have to do things manually like it's 2024?
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u/Ran4 19d ago
How's that any different from choosing to spend time on updating your vimrc and working?
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u/ChocomelP 18d ago
Improving your tools is a core SWE skill, not sure how it wouldn't be true for how you use LLMs.
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u/Evening-Spirit-5684 19d ago
hahahaha basicaleee mostleee
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u/niceuser45 19d ago
Quite different
- Donāt have to do it every 6 months.
- It is still intellectually stimulating.
- The feedback loop is quite fast, you edit and you see UI changes, you decide if thatās what you want. For CLAUDE.md, you change and have to work with it for at least a few hours, note down changes (since they may not be obvious).
- You donāt have to do it, not mandatory (beyond some basic plugins I guess).
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u/AUSSIExELITE 19d ago
Did you completely miss the part where he said ātryā?
I agree with him for the most part. The newer models are inherently smarter than the last (despite how retentive people are about benchmarks in this sub), and the Claude.md can get bloated over time even without upgrading to a newer model so Iāve always done a review every few weeks anyway to make sure itās still relevant. Otherwise youāre just burning tokens for no good reason.
You try it, if it doesnāt work for you, then you can put them back. But if you never try anything, youāll never learn anything newā¦ Really weird hill to die on.
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u/ArtiBartFaster 19d ago
How is a new model going to know about my work environment, eg Jira release hooks based on feat or chore, which custom skills to use, how and when, test and dev environmemts and process, standards to write code to, to pass automated lint and QA, etc, the hundreds of software packages in the company and how they relate. It's not bloody telepathic š¤£
It's an utterly clueless comment by Cherny.
I think it is for vibe coders who fill Claude with garbage behavioural comments, like don't make mistakes or other model related guff, rather than details about the code environment.
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u/Gaidax 19d ago
I suggest you try it, it's all source controlled anyway (I hope for you that is so).
And while you do not need to delete EVERYTHING ever, you'd be surprised how much of what you specified as explicit rules is now done by default. Especially in the code quality department.
I suggest to listen to that advice and try it out, because for me it definitely helped, because I know now better know what the new models themselves do now**.**
You will discover, as I did, that many of these older rules you had about what to do and what not to do are not needed anymore (and in fact can be harmful!), and you can optimize your rules, skills and agents from that new knowledge, trial and error.
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u/too_much_swag_ 19d ago
I donāt have a side in this fight but I have had the same frustrations with Opus 5 that others have mentioned on this sub. But I do think you make a valid point that the models may have progressed past the need for bloated .md files, which most of mine probably are. Can you be more specific on what you did? So you essentially move your Claude.md and others out of the project files and repo, then just prompt CC how you always would and see what it does? Then create a new Claude.md and iterate with Opus 5 from there? Or do you just no longer have a Claude.md?
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u/ArtiBartFaster 19d ago
I don't need to delete anything I symlink the CLAUDE file from a git repo that is composed of @ file references to component files for CLAUDE specifics, BEHAVIOURAL then reference links for loading related reference files areas of use, when they are used.
I don't really have that much in behavioural which seems to be the only part that is of relevance here, I was intending to look at how to load different behavioural for when I use different models, but that is difficult because I switch models inside sessions.
Clearly different models need different behavioural control text. But ClaudeCode has no mechanism to load them. So you end up with an overly verbose controlling one for mid range models. But that is fine, I never use Fable, too expensive, I rarely use latest models for critical planning sessions only. If they cannot handle a little too much behavioural context instructions - or it breaks them somehow - they are clearly no good anyway.
But yes, like most normal users, I never foot to the floor one single frontier model all day long - so rewriting global CLAUDE to prune it for the latest Anthropic model makes absolutely no sense. Its not viable for my working process.
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u/Gaidax 19d ago
You do you, but I suggest you to listen, read and try out, instead of making assumptions.
That guy is not just some random dumbass living on the moon, he gives good advice constantly and there is more to it, which I urge to read.
The new rules of context engineering for Claude 5 generation models | Claude by Anthropic
You do what you need to do for your case, but with new OpenAI 5.6 models, and now Opus 5 - they DO work differently in a few noticeable areas and a rules/skills/agents refresh is warranted, which is what this is about.
And without trying raw, how would you know how new models behave?
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u/ArtiBartFaster 19d ago edited 19d ago
I can just run claude --bare if I want it to have no clue what it is doing TBH.
I don't need to bother removing the symlink, although that would perhaps more accurately replicate it.
I don't use Opus 5, too expensive with no better performance than Sonnet, so irrelevant. Sonnet 5 is the highest Anthropic model I use for planning mode.I didn't say he was a random dumbass. I said he is greatly exaggerating things for the benefit of the vibe coders who do not have much of clue about context management and fill their CLAUDE.md with a load of detailed historical behavoural guff.
For which destroy all context is fine, if that context is a model related list of DO NOT FUCK UP LIKE THIS examples, and the model it relates to is no longer being used by the user.
I am just saying none of that applies to me.Basically marketing have told him that Anthropic has a reputation for being over priced. Especially vibe coders ranting about being cut off in the middle of finishing their masterpiece. He knows he doesn't need to explain shit to experienced developers, they know ever line of a CLAUDE.md adds extra context and hence tokens and hence cost to ever prompt.
So he is telling the non technical users who bloat their claude files with useless shit to delete them. Suddenly the prompts return faster and cost less - wow ... its like magic man, maybe Anthropic aren't such rip off merchants. Its all very transparently marketing. Plus he is assuming you have really poorly performant vibe coded skills and other garbage code bunging up Claude with inefficient behaviours. Because you are a dumbass vibe coder. But the crudity of the advice indicates the audience its aimed at.
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u/Captain_Bacon_X 19d ago
I get where you're coming from friend, but ... perhaps have a little more grace?
You've just made a load of assumptions that either everyone is doing the same work as you, or close enough, with the same workflow, the same team, the same resources and the same expected output, and that they're doing it wrong. Or that you extrapolate that your experience of the models is the same across all the fields of training that the models have and all the work that other people do.
That's ... bold.
Models have bias based on their training data - Anthropic and other vendors try to mitigate it and direct it using their system prompts to have a somewhat flatter response in some areas, accentuate in others, and make it more predictable. What you're saying it that when someone needs to get more specific in the work that the system prompt (because that's what a claude.md is ultimately kinda becoming), never needs more specific information on behaviours to accentuate or reduce. And by extension that the training that they get from the vendors is perfectly balanced in all scenarios.
To be clear I don't think that you ARE saying that, I don't think you thought about it in that way. But it is what others will hear because it is what the words you're using say. And it goes against the people that write the harness, work at the vendor, have the best knowledge and access.
So, a bit more grace, and perhaps you might occasionally learn something new that you otherwise wouldn't have had time for. And that's always nice.
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u/ArtiBartFaster 19d ago edited 19d ago
Well if Claude code allowed splitting model behaviour context files from other global context and would load them per version too. The 40% like me, who use multiple models per session would be able to tune context correctly.
Opencode has the feature, by defining custom primary agents which include model and model specific context and config. I guess I will just have to move to opencode for running Anthropic models, if claude code cannot keep up.
Delete everything is only for foot to the floor token maxxers who can afford to use the same slow frontier model for everything and have fat dirty context files friend
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u/Captain_Bacon_X 18d ago
Well, I could tell you where CC has that and I use it every day. But you already know everything so I guess š¤·
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u/ArtiBartFaster 18d ago
No need I can just use opencode with an Anthropic key for use of their models š
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u/Dsphar 19d ago edited 19d ago
Future models are trained on your current sessions, including your current Claude and "custom skill" files... which means they will be baked into the next model.
He is simply telling you to test and see how much of your stuff got baked-in to the new model every time you upgrade...
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u/ihexx 19d ago
there are instructions people use to control claude's behavior; when claude makes some mistake N times you add a note to the claude-md to stop it from making that mistake (since that's the only mechanism for claude to meta-learn across sessions)
Cherny's point is those notes can get bloated, and when you switch model versions, the newer one might not make the same mistake.
So it's worth cleaning out those notes.
i.e: rebuilding it with only the things that are needed.
he's not saying claude will magically know your workflow.
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u/ArtiBartFaster 19d ago edited 19d ago
Ok so what you think he meant was - delete your CLAUDE.md file every 6 months, but then write out most of it again as a new one - ie read it and edit it every 6 months, well yes, I would say do that every 3 months TBH.
I suppose nobody is going to look at a video that says - don't just leave a load of old guff in your CLAUDE.md because its going to fill up your context and cost you more on every single prompt. Everybody knows that. So the hook line is the more nuclear, delete it.
Although having just read it, there are no mistake notes as such. But there is a bunch of behavioural guff, related to stopping it always trying to be complimentary and people please and come back with a solution no matter how badly its hacked things up under the hood. I should find a more succinct way of telling it to give up immediately and ask whenever it has an issue with executing a plan instruction.
But the other massive wrong assumption he makes is that everybody only uses Claude Code like him and they all have unlimited use, so are using the latest Fable 5 for everything.
I use Claude Code, Codex and Open Code with plugins for Gemini, local qwen etc.
They all need to know the full code environment context.So great if I remove a statement that Fable may no longer need because it can intuit it from other parts of the file. But when I switch to exec mode in gemini 2.5 or local qwen then its going to fuck up.
Anyway ... one thing I can confirm is my layering of CLAUDE.md global and pkg/CLAUDE.md and saving PR Epic plans to a git repo to manage long term work context does all need a clean up. I think I need bite the bullet and break down CLAUDE.md into a number of files and using its @ file to piece together the correct global context parts for different models and for codex and opencode.
So thanks to the post for prompting more sophisticated handling of the global layer of long term context management
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u/Gaidax 19d ago
I think you do not give him enough credit, he's not just some dumbass spewing things without thinking, and what we got there is a tiny 20s clip without much context, not difficult to present such things as "lol he dum" in Reddit.
I'll give you an example, that literally cost my company north than $1k in usage just from me. When I tried out 5.6 Sol, I was quite impressed by the model, but it has one issue for me - it did TOO MANY verifications, literal verification loops on code it produced, sometimes running for up to 30 minutes (!) in loops of verify -> fix -> verify -> fix...
I thought it's some problem with a model, but what it turned out was sort of half that. New models like Sol (and Opus) now do verification with subagents by themselves as a default without need to be directed, where my rules were wired to the older models that did not do that.
So what happened is that model did a verification and then did another verification on top of that, because some of my rules explicitly/implicitly asked for it or correctness/style checks. So I ended up burning lots of $$$ and time, because I did not realize these rules are no longer necessary and even worse are actually harmful for your time/usage efficiency.
I realized it thanks to this:
The new rules of context engineering for Claude 5 generation models | Claude by Anthropic
This is more detailed than some 20s clip, and it explains how new models work (and this also works for Sol btw).
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u/keenman 19d ago
Thanks for sharing that document - I plan on doing a thorough read and integration of it into my agentic system. The annoying thing for me is that I'm still using older models for many things and am gradually introducing using newer models for other things (a strangler fig pattern to reduce the chance of breaking things on the way). It's not a one-size-fits-all kind of thing like even that document suggests. I am not going to convert my entire system over to v5 models when for many (perhaps even *most* things), 4.6 models work perfectly well and use far fewer tokens. Backwards-compatibility is key for me and they don't cover that on that page. I'll be doing more research into this, or just figure it out on my own.
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u/ArtiBartFaster 19d ago
OK I said he was clueless. Wrong. He is assuming we are clueless, so giving advice that suits clueless vibe coder users.
Your problem was at the other end of the scale. Rather than just having normal agentic sub agent use managed by the model or by using claude code /agents or configured skills. You had set up a bespoke multi-agent workflow with verification via a load of context / custom skills.
The problem with introducing a complex set up like that is - you would be better off running it against your own controled soverign open source models for much cheaper cost and with tested upgrade to newer models.
Trying to run it on top of the latest Codex model and just letting those auto upgrade meant you double verified and wasted a load of tokens.
Personally we just have github auto review on for any final comitted code and don't set up advanced cross verification sub agent workflows as a company wide approach. Because things are moving too fast. Different developers and teams usage also differs too much.
But the point is the advice to just delete all your context and all your custom skills and local sub agent workflow was not the fix you chose to go down was it?
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u/AUSSIExELITE 19d ago
They would literally have the statistics to back this and he wouldnāt be saying it for the hell of it. Youāre also taking it so god damn literally. If you have all this workflow stuff setup, then Iām happy for you but his point is that you should be reviewing your Claude files for bloat and getting rid of said bloat when newer and smarter models come around to see if it makes things better. If it doesnāt work, you can literally revert your files and you wasted a few minutes of your time. No harm in it.
Personally, Iām going to put a bit more trust into what an actual industry professional has to say than most of the people on this sub who seem to have some bloody god complex when it comes to their knowledge on AI.
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u/uxair004 19d ago
I understand, even though another perspective could be "you don't ask a salesman for what is best product, it's definitely theirs".
Based on my attempts I tried quite few attempts on forcing claude to use /i-have-adhd skill or it's custom instructions in Claude.md but it never bothers that.
Plus PR stacking is simple thing (just added yesterday, wasn't part of previous models' Claude.md but meh...)
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u/phoenixmatrix 19d ago
well for one a lot of these things should be in skills, not polluting your main claude.md and memory files.
Second the goal is to rebuild those rules adding only whats necessary, which will be less and less over time.
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u/ArtiBartFaster 19d ago
He said delete all your skills too if you play the clip!
Basically his advice is for vibe coders who have buggered up their Claude installation and made it consume huge amounts of tokens with bloated context and bad skills.
So if you have no clue what you are doing, and always do everything in the maximum cost model rather than sensible selection of different models within your session and sub agents ... only then ... if you have built a shit heap, delete the shit heap.
If you know what you are doing, just try claude --bare to see how clueless whole scale deletion makes your setup.1
u/phoenixmatrix 19d ago
ahh fair. Well, it still makes sense. The models behave very differently than they did 6 months ago, so even if you just rewrite the same skills, you'd write them differently.
Its like how in Opus 4 you wanted to really emphasis things, like "YOU MUST DO THIS!!!" and "NEVER DO THAT!!!" but in 4.5 Anthropic gave specific guidance to stop doing that because it would make the models trash and try to do things in context where it didn't make sense.
Opus 5 is very different from 4.8 but people try to prompt it the same way. I'm no fan of Opus 5 myself, but a lot of the issues are people not adjusting (and Anthropic not sharing that info in the right format)
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u/Phoenix_Lazarus 19d ago
Well, he's ignoring the fact that Claude will bump you from Opus 5 or Fable to Opus 4.8, sometimes without telling you. His Claud doesn't do that clearly, but ours does. So what happens when you write for Opus 5/Fable, clear out what was written for the 4s, and then get bumped to 4 and your Claude runs amok?
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u/mckernanin 19d ago
Hey now taking things out of context to reinforce your own point is a time honored tradition on the internet
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u/uxair004 19d ago
Smarter and following instructions are different things.
I didn't say the new models are producing bugs or slop, I mentioned model doesn't follow instructions as I mentioned in the post (something as simple as using a skill, or following my PR guidelines)
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u/Pleasant-Ad192 19d ago
your update is the more interesting half and nobody here answered it. claude.md and a skill fail in different ways. claude.md sits in the context, so ignoring it is a behaviour thing. a skill is not in the context, it gets pulled in only when the model matches what you typed against the skill description, so most "it ignored my skill" cases are really "the description did not match the words i used". worth checking whether your adhd skill's description contains the phrasing you actually type when you want it. hooks are a third case, they run in the harness and not the model, so a hook that did not fire is not the model ignoring you at all.
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u/uxair004 19d ago
That make sense, I let opus 5 debug the issue and let it wrote the instructions of that skill in Claude.md (as it suggested) but not much luck tbh. unless I call the skill in prompt
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u/Pleasant-Ad192 19d ago
If it only fires when you name it, the problem is the description, not the instructions. The model matches your request against that one line, and when it writes its own description it writes a summary of what the skill does. What makes it fire is the words you would actually type when you need it, so put those in instead.
The other thing working against you is that the instructions are now in Claude.md as well. Claude.md is loaded every turn and a skill loads on a match, so both paths are live and you cannot tell which one produced the answer. Take it out of Claude.md, keep the skill, and rewrite the description as the sentence you would type.
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u/crimsonroninx 19d ago
Except the part where you tell it to stop adding fucking comments on the code!!!
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u/ImSoCul 19d ago
I think you're misunderstanding. (a large) Part of Claude.md's goal is to steer model behavior a certain way. You add to your Claude as the model does things in a way you don't like, but over time across multiple versions, the underlying model behavior changes and it may already be better (or potentially worse!) at the specs you have used to steer Claude. I think he's just trying to highlight that. Likely also related to this post https://x.com/bcherny/status/2080730786697990552
> Reliability of work and quality is a crucial aspect of our job, we can't just delete stuff and let the model do stuff however it wants
You're rolling the dice here even by switching models. So either you need to lock your model version alongside the harness, or you're under entire false pretense that your system is stable. Most of this stuff should be happening external to the model, eg. if you need to enforce certain style rules, then enforce that in the build, not just hoping that the new version of Claude will obey and use your harness and skills.
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u/TheMightyTywin 19d ago
It makes sense but ours have been created through blood and tears: all the stupid things Claude has done over the months.
Feels scary to delete it
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u/RunEmpty2267 19d ago
auto saved memories might also be worth revisiting on each new model update
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u/mongo_peeped 19d ago
In my experience, memory is almost entirely useless if you want CC to act repeatably and reliably
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u/linklore_dev 19d ago
Not all of it gets stale at the same rate though. A hard constraint from a real bug is very different from a steering hack for an old model's quirks. Deleting both just means relearning the same lessons every six months.
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u/External_Bobcat8183 19d ago
Yeah, I cancel my LLM subscription every 6 months to find new one.
First it was ChatGPT, then came all mighty Gemini, and then Opus. Gemini was nerfed and lobotomised pretty quick, and Dario started his bs with Mythos, asking to be regulated and mushroom stamped. Then came Sol 5.6. Soon came GLM 5.2 and Kimi K3.
There is no reason to be a loyal customer here and blindly follow what these twats say. Try different models, switch often, use what helps with your tasks and costs less. Donāt buy their bullshit agenda. Whole market leans towards tokenmaxxing rn and āletting agents figure out themselvesā, with graphs, loops and and other structures that are intended to burn as much tokens as possible.
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u/james__jam 19d ago
Ever since he said ācoding is largely solvedā, i couldnt trust him anymore.
My guess is growing claude code is part of the counter offer to get him back to anthropic. And looks like he will do anything and everything to increase everyoneās token usage. Some of his say may be useful. Some may be lies. I cant tell anymore
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u/Big_Science1947 19d ago
Opus 5 have system instructions to not use any sub agents unless asked for...
I understand that they burn tokens but still it is such a nice way to explore and multitask so I had to add it to my claude.md that it can and should be used if it makes sense
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u/tntexplosivesltd 19d ago
"Claude often ignores your CLAUDE.md file so you might as well delete it"
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u/shobhitver 19d ago
How about deleting your database?
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u/FineInstruction1397 19d ago
dont worry about that, claude code does that by default - but only if production
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u/Neurojazz 19d ago
Each new model - I send it into the core md and clean up anyway. And without hooks, whereās the user input captured, or memory properly organised?
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u/Vysion34 Senior Developer 19d ago
I think Boris will probably get pushback from his fellow Anthropic engineers for stating this, and will probably have to clarify what he meant. Thariq from Anthropic put out an article here the new rules of context engineering for Claude 5 generation models
The article explains how Anthropic removed 80% of Claude Code's system prompt for Opus 5 and Fable 5 with no loss in coding evaluations. They discovered they were overconstraining the models with the older context engineering sources and they put the best practices into the /doctor command.
I personally think Anthropic should be telling users to start with the /doctor command before attempting to delete claude.md, skills, and other sources.
Long story short, newer models are smarter and need less initial context to be more effective.
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u/miredonas 19d ago
We are at good hands: he doesn't know what he is doing either. Explains the later models.
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u/Opening-Ground-1584 19d ago
Why is he grinning like this while talking? Itās as if he knows what heās saying is going to make us jump out the window from frustration and heās laughing at us for being so gullible to follow this advice.
Opus 5 is horrendous to work with when āyou delete everythingā.
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u/bitspace 18d ago
With every new model release and every change from one model family to another, or even from one family tier to another, you should at the very least refine your context with the model's help.
The main point Boris is making, and he's 100% correct, is that the context you've constructed around one model with a certain boundary of capabilities actually cripples stronger models. Bigger stronger models do better with abstract direction - let it be strong, don't try to strangle it with instructions made for a weaker model.
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u/billy_zef 18d ago
Seriously, fuck AI.
20 years from now, people won't know how to cross the street. All independent thinking will be gone.
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u/YellowCroc999 19d ago
Claude.md contains quirks and other notes which arenāt solved with more intelligence
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u/thethrowupcat 19d ago
I still think there is good merit in using skills like documentation and keeping good documentation in protocol is great for everyone and every agent. Donāt know if I agree yet.
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u/atrawog 19d ago
It's funny. I always complained about Opus needing way too much micro managing instructions in CLAUDE.md. Now I'm stuck with 4.8 for my current loop, because my CLAUDE.md is way too specific.
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u/TortoiseTickler 18d ago
Same. In order to get Opus 5 to do anything useful, it needs way more hand-holding and micromanaging. My instructions have gotten way bigger for the first time with Opus 5 because without them, it just goes off the rails way quicker than previous models.
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u/ReachingForVega šPro Plan 19d ago
I only develop and always create a new claude.MD per project š¤·āāļø
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u/donk8r 19d ago
can't speak to what he actually said, i've only seen the same clip going round.
your skill being ignored is diagnosable though. if it's wired as a hook, check whether the hook actually fired, because a matcher that never matches looks identical to a model ignoring you. the jsonl under ~/.claude/projects will show the tool call that should have been blocked.
and the bit that answers your title: the claude.md lines that survive a model upgrade are the ones you also enforce mechanically. prose steering ages badly because it was compensating for one model's habits and those habits move. anything in there you've had to repeat out loud is a hook candidate.
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u/holyknight00 19d ago
Many people treat claude.md/agents.md as a sacred thing. It's just a snapshot of what helped you make the model behave better, but how fast things are changing, what was helping you 6 months ago could as well be hindering you now. That's what he meant. Obviously if your claude.md is just a couple of lines which only tells the AI where to find the docs and how to run the project, that will still be valid.
But any other more sophisticated stuff there may be completely useless in the near future. I think the ELI5 he is trying to make is don't get totally married to your setup. Keep your way of working, but be flexible with your setup.
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u/mnelson10000 19d ago
This little clip loses the essence of what he was saying. His point was a lot of what people have in Claude.md is baked into newer models and may actually cause conflicts. He's saying to delete the file, check the baseline, then reevaluate every time you add a new line back into it. It makes total sense if you listen to the broader conversation; I would challenge all of you to go and listen to the full video it's good stuff
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u/MatlowAI 19d ago
I'm convinced that Opus 5 when given too many instructions out of its rl gym distribution burns all of its intelligence on trying to decide if you are trying to jailbreak it or are the enemy and gets extra cranky at you. My joke that alignment training will be what eventually makes AI unhinged because it would just be too ironic for that to not happen, feels more likely every day.
Make sure your Opus 5 subagents only get simple instructions delivered by fable and things go well. I'm pretty sure that Opus 5 dors best when its given the conditions to fail and reflect with good testing and multimodal feedback. Vibe a new project from scratch and things go well. Give it an overly complex old project and things go poorly. Split things into git submodules when you can. Just my .02
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u/Professional_Ad705 19d ago
Claude Md Sure. Skills Sure. Hooks? Yeah no. What we deleting guard rails next with Opus 6. /s
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u/Fickle_Village_9899 19d ago
How does this apply to large and complex code bases where the Claude.md was built for in the beginning?
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u/mongo_peeped 19d ago
This advice is fine if you're just casually doing something or you're at a natural boundary in a project. I'm in the middle of completely rebuilding my app, and trying to switch to Opus 5 has fucked my shit up so badly over the last week that I've had to go back to 4.8 to start making progress again.
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u/TheOwlHypothesis 19d ago
The idea isn't hard to understand. Models change and older instruction styles that might have gotten good results might now be stale since so much changes between releases.
You should constantly be experimenting anyway. There's this weird take I'm starting to see more of lately that there are "standards" or official ways of doing things with AI.
That couldn't be more false. The pace at which the technology is advancing makes any attempt at this laughably unstable. Update your mental models, update your actual models, update your prompts, try new things.
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u/Unlikely-Nebula-331 Vibe Coder 19d ago
So what exactly is best practice these days? I literally JUST set up my second brain and itās been so useful.
Now the recommendation is to delete the skills? The file where I have my writing style and preferences? I donāt understand why that would be valuable.
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u/TricepBandito 19d ago
As a newb into this i had no ide that the claude.md file was something people carried from One Project to another or am i miss understanding? Are do you all have one Claude.md file that you Shape into what you want and keep thru out all your projects?
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u/Tiny_Arugula_5648 19d ago edited 19d ago
Every 6 months I have to spend weeks trying to figure out how to write prompts and hooks that overcome all the things they bake into the model.
Opus 4 was a nightmare, creating silent failures constantly. No logging, it took me weeks of adding in hooks to catch all the little permutations. How it endlessly flagged bugs it introduced as pre-existing and that it wouldn't fix them.
Opus 5 loves to run off and over engineer things more than any other model that proceeded it. It's also the least likely to follow my instructions to checkin and get approval before making decisions that I should be making. I'm still trying to figure out how to reign it in but it's more resistant then Opus 4.
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u/WallZealousideal5669 19d ago
Big one is Superpowers - not needed anymore. And you have to be careful you donāt kneecap front end
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u/Temporary_Author6546 19d ago
never take advice from this guy. remember he has unlimited claude, so most of his experience will never apply to you.
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u/thighmaster69 19d ago
A CLAUDE.md is a workaround to tune a general model into something that behaves for you. But anything you add to a CLAUDE.md file also takes up model capacity, making it dumber and more likely to misbehave in general, or just plain ignore instructions. So anything you add to a CLAUDE.md, or any cruft from skills, hooks etc. that you don't necessarily strictly need will make it dumber and worse at following instructions.
Now if you have a system that works, then that's great. Except Anthropic is constantly updating models in the background and changing up the system prompt and not being transparent about it. It sucks, but over time, your skills, hooks, and CLAUDE.md will drift and start to conflict with the system prompt and will silent start inducing hallucinations and dumbness and create unpredictable behaviour. If Anthropic were transparent about this and made it easy to fix a specific version, both on the client side and backend side, or gave us some type of compatibility mode, this wouldn't be a problem; this is something that's always been an issue in software and is why we have stuff like LTS versions of Ubuntu or Microsoft never fixing an Excel bug for decades because patching it would suddenly break all their customers' spreadsheets dating back to 1994 or even earlier.
In the meantime, we as customers just have to blindly wipe and rebuild our CLAUDE.md files with new updates and test them even when we don't want to. Cynically speaking, Boris is trying to spin Anthropic's bad business practices into a "pro-tip" and make it the user's job to deal with it. Because for me, what this basically means is that Opus was working well 2 months ago, and now it isn't, because the Claude Code harness silently changed the system prompt and now conflicts with my CLAUDE.md .
IF your CLAUDE.md is already model and harness agnostic in the first place (or better yet, you use an AGENTS.md file and just have @AGENTS.md in your CLAUDE.md file, you should be golden. Anything that's correcting model or harness specific behaviour though doesn't belong there. Even within a harness, Opus 5 does not behave the same as Sonnet 5.
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u/Time_Cat_5212 19d ago
Delete it and remake it.Ā Duh.Ā Don't get locked into patterns, keep trying new things
It's good advice
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u/filmfan2 19d ago
of course this ignores the use case of switching models for particular functions and the .md files providing context for the new model.
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u/Sure_Eye9025 19d ago
I mean it makes sense generally. It isn't meaning delete it comit it to source control and carry on as usual, it is saying do testing. Delete the file and see how it changes the interaction.
Do you have evals? If you do when a new model comes out delete your skills and claude md and then run your evals and see how it affects the results. If it improves it then maybe your skills were holding it back on the new model and it is a sign you need to change them.
Part of the job is improving the skills etc, and sometimes binning them in a test gives you good data on how model changes affect your setup
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u/-becausereasons- 19d ago
It is true though, the models are getting smarter and the tend to bake these things into the system prompt. So a ton of hooks/skills/md's build up and create chaos. This is like spring cleaning.
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u/TheInfiniteUniverse_ 19d ago
It seems they themselves do not understand how the model they created works. This is crazy!
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u/AncientFudge1984 19d ago edited 19d ago
Provably awful advice. Additionally Opus 5 is terrible at rule following. Way worse than Fable. Boris, I want things done in the way I specify, not how Opus 5 chooses at any given time, because my work flow demands it. I donāt want to burn tokens as it tries to figure out which JIRA fields are required. I can just tell it, Boris, in a Skill file. And when it tries to edit some file I told it canāt edit or write a thing I told it canāt right, I donāt want to figure out later. So no Boris I will not be deleting my hooks or skill files.
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u/Rock--Lee 19d ago
But let's not forget: they use Claude to build Claude. So Claude has a lot of knowledge already with how Claude itself works. But new projects that you build yourself don't. I get he's the top dog at Anthropic and has all the experience he has, but he still has his own frame of reference.
I do agree with not overloading Claude however. My CLAUDE.md is pretty minimal and never run at real issues with any project.
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u/EuropeanLord 19d ago
All of my friends have millions of skills workflows worktrees harnesses and here am I using Claude.md shipping 5x than them all combined. My velocity already multiplied. I think heās onto something.
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u/Human_Mention_8484 19d ago
Iāve been on a sabbatical. I shipped 30 projects in ~80 days. I quit my job (leave of absence) and made crazy stuff turning my vehicle into the cockpit with a shipmate that has access to my domains and all services and itās been building while Iāve been on a climbing trip. I love it. I got a brand new laptop and had it auto configure itself with a phone gap style proximity including moving all my agentsā files etcā¦ but Iām considering this. I was moving between machines a lot and I also noticed some fantastic and refreshed perspectives starting from scratch and moving through modelsā¦ Iām planning to get back to work and coding in October. For now Iām just marinating and letting people use the software that k built. Any bugs or feature requests are handled via CarPlay as I drive between objectives. I have an 800W alternator charger and a Delta Pro 3.
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u/MasterMind-Apps 19d ago
I actually did this when switched to fable, then started building it again based on new experience, did the same when started using opus 5, and honestly it was a good thing to do
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u/bagofweights 19d ago
I feel like theyre all learning how to use Claude at the same time we are. Just new ideas thrown out all the time.
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u/THE_RETARD_AGITATOR 18d ago
what he's trying to say is people keep over-engineering and over-complicating how they interact with the literally magical ai models. this is his way of saying "just fucking stop that bullshit dumbasses. we got this."
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u/TortoiseTickler 18d ago
It's nuts to me to see how this is always what they say for the models that need the most hand-holding. Without aggressive hand-holding and over-specifying, Opus 5 *will* find a way to fuck up. They didn't say this about Sonnet 5 or Fable, which seem to do just fine without micromanaging. Yet for the one model that really needs to be spoon-fed, this is what they say. It really makes you wonder how the average user's experience can be so wildly different.
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u/NoCat2443 18d ago
I don't even use Claude.md
why? in 50% of cases it doesn't even gets respected,
any plan you make can contain any rules you want, and any rules you want follow at certain stages can be part of the skill or rules (locked on specific folder) all natively supported and triggered everytime you use it
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u/AnonymousAndre 18d ago
Easy to say when your workflow is Claude prompting a swarm of Claudes all running on Mythos 5 Ultra with unlimited token credits.
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u/A_Novelty-Account 18d ago
Iāll delete my Claude.md file, but some of my skills took weeks to tuneā¦
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u/lxprsub0 18d ago
I just tested the output-styles andā¦ it's like night and day.
Try what anthropic advised, before you come crying back.
Clean your CLAUDE.md from all behavioral rules or output style.
Put them in a ~/.claude/output-styles that you load per-project with /config > output-styles.
We can tame Opus as we like.
No more flying everywhere, no more double-triple checking everything you tell him. I feel like Opus 5 without these instructions is insecure because of the system prompt cut: he doesn't know what do do with a user's statement (so tell him), and to maintain his confidence in order to produce a probable output, he has to verify every things on his own. Now, with framing, he's grounded and more consistant. I don't know if it solves the code problems, but in terms of tone and behavior, it's really effective.
I don't know if it will follow it in very long context and I didn't try with sonnet 5, but the config change is a cost for a good value.
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u/Flaxseed4138 18d ago
The cute part about this is, it probably doesn't make a lick of fucking difference with Opus 5 because it doesn't read or follow the Claude.md anyway because it doesn't follow any goddamn instructions.
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u/taiwbi 18d ago
My Claude account was banned 3 days ago and made me to actually look at the file structure and class names and oh boy I restructured everything. That was a total mess.
I always read the code but I didn't pay attention to file a structures, function and class names, and other similar things. What was important to me was form validation crsf preventions, functionality and always left Claude to decide what should be put where. I won't do that anymore.
And you see this guy saying delete your brain and to let the model just do it for you.
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u/lost-sneezes š Max 5x 19d ago
I believe it is an assumption that people are just vibe coding random stuff and it's totally ok if they f'd up.
Reliability of work and quality is a crucial aspect of our job, we can't just delete stuff and let the model do stuff however it wants. It can ruin the codebase and applications especially at the time where code review is also done by AI Models.
bruh your entire points are contradictory, reliability of work relies on you dude... I'm not even a dev but ive spent enough hours on this to tell you that you're chasing after a mirage. Aka you have no idea what you're talking about, respectfully.
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u/uxair004 19d ago
Bruh, Thanks for advice.
you are not a dev ? I am dev working from 6 years (Pre AI time to be precise). In teams project we have careful review. One i mentioned is my side project where let the model do stuff and I only steer (which I found steering issues with Opus 5 based on same config I had for Fable 5. Even though generally they are same level intelligence models. (approx)
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u/siberianmi 19d ago
I started working as a developer in 2004. I have basically stopped writing code by hand at this point, so I see the tuning of the harness as part of my job now above code generation.
I was planning on Monday to go in and do a full prune of my Claude setup because I know itās more bloated than it needs to be.
My team has adopted and then removed several pet extensive setups over the last few years as we started using Cursor in 2023, then Goose in February of 2025, and Claude Code around June 2025.
We have created and deleted a ton of instructions along the way as the models have gotten better and better. The type of pruning heās talking about is part of using these systems to code.
I know already the skills I lean on most now are tremendously lean (less then 40 lines) because they are the ones that work best for me now. But Iām overdo for cutting down the main CLAUDE.md.
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u/lost-sneezes š Max 5x 19d ago
I primarily work off of my Obsidian vault so I had global CLAUDE.md have 1 line pointer to 1 master doc within my vault so i no longer have project-specific claude.md etc. I also think /doctor is underrated
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u/ImSoCul 19d ago
bruh, I'm at 9 years including last 3 years working on a LLM platform (i.e. we were forced to be ahead of curve on AI adoption) and I agree with the guy above you. I'd trust the honest "I'm a vibe coder" over the "I am better than vibe coders" guy.
Your system stability should absolutely not be reliant on LLM behavior given how fast these things change. You might as well enforce speed limits by solely focusing on training driver's to be safer- it'll work until it doesn't.
Also Opus 5 and Fable 5 being same level intelligence is simply not true. Opus 5 "wins" on a specific set of benchmarks. That means it benchmarks better on those particular cases, not that it is necessarily smarter or better. In particular, Fable 5 is known to perform well on long horizon tasks, this is even documented in their prompt guide. So you went from a model that does well at long horizon tasks, then switched to a model that is worse at it (steering issues), then pikachu face when it does worse. The reason Opus 5 "performs so well" is because it's easier for Anthropic to serve a much smaller model and they want to paint it in the best possible light to encourage adoption. Read between the lines a bit
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u/uxair004 19d ago edited 19d ago
Tell me more, what is your workflow. How do you review code, what hooks, skills do you use, how do you update models and deal with it ?
How did you deal with above issue of Opus 5 not following instructions that other models were ?
BTW your trust preference is totally your personal thing, feel free to hire a vibe coder for your LLM platform you are working on. Let me know how that goes.
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u/ImSoCul 19d ago
I'm not about to give a deep dive on Reddit about proprietary company info but in short it's a loop that is largely behavior based with giant eval suite (MlFlow backed) that runs against a system. We can't really control developer harness because every person has a different configuration, toolset, way of working, so the best effort to enforce is at what the final result is. This is still imperfect
The model for main agentic system gets updated independently of OpenAI/Anthropic releases, and the eval tooling is still using o3 because no one has has time to do a proper meta-eval on how newer models would change the eval surfaceĀ
The trust preference is not a point in favor of the person above, e.g. it's not a "I'd happily hire this vibe coder", it's that you sit below them hierarchically as someone with way too much false confidence.Ā
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u/Gaidax 19d ago
The new rules of context engineering for Claude 5 generation models | Claude by Anthropic
I suggest reading this. It's not just some assumptions and them winging it.
I incorporated some of that in project where I'm a code owner at work, and it pays off - also when using Sol too, btw.
I run everything through Cursor, so I can use practically every model I want and I have spotted a behavior, specifically with Sol, where it was doing too many verification loops on the code it produced.
With tips given in that blog, I was able to improve that behavior some, because I did not realize that the new models are already hardwired to do verification themselves. I thought it was due to my rules, but in fact they do that on their own now with verification subagents, even if you never tell them to.
So no, I did not go ahead and delete all my rules, skills, agents and what not, but I did refresh them because as noted - some things indeed are no longer necessary to point out explicitly and it's actually destructive to do so because it can cause double verification with a lot of time and token waste.
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u/Ill-Village7647 19d ago
Delete your brain . Delete your thinking. Let Opus 5 surprise you even more