I recently had Claude Fable set up a new project for me and I pointed it at some existing projects to use as a guide on how I like to structure things. It created, unprompted, an AGENTS.md file and a CLAUDE.md symlink to AGENTS.md
I didn't even have that symlink in any other project - it just did it. I think it saw that one of the projects I already had was set up by Codex and that project had an AGENTS.md so perhaps it inferred that I was using both Claude and Codex, so it was politely covering both? Or maybe a recent change made this behavior default?
I was surprised and I hope they continue to seek standards.
Seems agents understand their own bugs now. https://github.com/openai/codex/issues/9252 has 88 thumbs up and a workaround (switch to raw mode with Alt+R) found in a comment. Codex suggested the workaround to me today when I complained about its multi-line bash command being corrupted on paste because of the two-space indent in Codex's code blocks.
Anthropic in 2025: We can use our dominant market position to degrade the harness experiences of our competitors because they will never adopt CLAUDE.md
Anthropic in 2026: We are losing our market position. Users who adopted other harnesses have a degraded Claude Code experience because it doesn't recognize their AGENTS.md
Sounds like free market at work to me. I am just glad there is quite a lot of competition in a field that I would have assumed would have huge costs of entry
Once I asked, puckishly, Claude Code to “follow the instructions in this directory” when there was only an AGENTS.md there.
In the manner of someone finding a dead mouse and holding it up for examination CC said it could find no instructions but perhaps it should check this AGENTS.md file.
Had a silly exchange with Codex: I had an AGENTS.md file in a directory that was a symlink to an already-created CLAUDE.md. On my first prompt to Codex, it decided to point to me that my AGENTS.md specifically calls out directions to Claude, and that it would generously re-interpret them as directions to itself, and that maybe I should fix my AGENTS.md to reference the correct agent.
> “I’m thinking about banning Claude Code at Shopify until they change their mind and read AGENTS.md and .agents/skills etc.,” Lütke posted Tuesday on X.
I heard some of their employees sent to do some PR in podcasts: they are definitively disconnected from the reality.
Maybe internally they see really unbelievable things, but my impression is that they pushed so hard on agents that they don't have the grasp of the situation.
Finalllyyyy!! We need industry wide standards. I come from the 3d industry and oh god changing softwares and adapting to different hotkeys it's a pain. I have always thought every industry should be standardized for the sake of the users.
Remember they didn't do this because they wanted to help community, they did it because community was angry and they were losing users to other harnesses.
Doesn't look like Anthropic care about dev community
Claude also checks your settings.json first, and if it sees a default there it then prefers that over anything in CLAUDE.md. This is particularly nefarious as they ship logic to presume a default if a setting is not there in settings.json, even if there are instructions in CLAUDE.md for exactly that.
For instance, say you added "do not add 'Made with Claude Code' in any issues, pull requests or wiki entries" in your CLAUDE.md. So far, so good.
Well the latest update now looks for something in your settings.json. Since you don't know about it, it is not set. Claude then says "not explicitly set, so now it is true by default". It completely ignores your CLAUDE.md.
Wait, what?
You shouldn't be shipping logic that arbitrarily redefines the behavior of the program, especially if your new logic actually ignores your own configuration or directives.
yep, all i want is freedom to make a workflow where i don't feel tied to one provider, CC is exactly what i don't wanna get trapped in. I'll happily use claude MODELS, but if it means i have to keep learning two harnesses side by side to keep using one particular provider, then the second i can easily replace it, i am going to(even if its a small drop in performance).
This project uses `AGENTS.md` as its agent instruction file (kept provider-agnostic).
Treat any `AGENTS.md` file exactly as you would a `CLAUDE.md` file — at the root level and in any subdirectory you are working in.
On many filesystems, a lot of data about a file is not attached to the content of the file, but stored in a master filename and metadata table graph tree of some sort, and the address offset within that metadata used to retrieve the contents on disk can be a duplicate of another entry, without that situation instantly leading to a filesystem driver crash. Some filesystems officially support such duplicates as well as equivalents of HTTP 3xx, some you can just do as a matter of fact and fsck would have some words about it.
Default filesystems for all Unix, Linux, WinNT, all do.
Yes. The thing is that creating a link will not do it recursively for all subdirectories. Even worse, in the subdirectories I didn't want to place a claude.md in the first place but just have agents.md.
That was the idea.... For the toplevel it works because of the @AGENTS.md and this is also the part the link would solve.
fwiw, i am with thariq https://x.com/trq212/status/2092302273099796842 in that prompts should be tuned for models and in fact blindly applying agents.md is probably an antipattern unless you want all models to basically converge to some common ill defined of instruction following - good local minima, bad global minima for model diversity and exploration of intelligence.
aka, sometimes it really is too early to force a standard
If you want this it's trivial to add an AGENTS.md that simply says "if you're Claude read CLAUDE.md, if you're Astra read ASTRA.md". A common entry point is good regardless.
Wasting turns? That is silly, use a better harness. Also token usage can mitigated by incremental discovery instead of stuck 5k+ worth of tokens in the AGENT/Claude md file.
depends what you're doing. if you've got a specialized agent deployed in prod, of course your evals and prompts will be targeted towards 1 specific version of a model.
on the other hand if it's just a local coding/"use my computer" agent, i highly doubt the effort in maintaining different prompts is worth any gain in performance
No thanks, I'm not tuning a bunch of files just for things to break when I switch models or a new one comes out.
I'll just use my one-size-fits-all AGENTS.md file and tweak it when the one of the clankers screw up. I don't have time for such busywork.
Actually, I will append extra rules to CLAUDE.md (which imports AGENTS.md) since there is a hook there, and Claude has its own foibles. So I'll backpedal a bit there.
In a "one LLM only" environment, your instructions are by default tuned for said LLM.
In a multi-LLM environment, roughly nobody will keep separate sets of instructions for each. It's not a realistic take.
On top of that: If your LLM is so bad at reading that it can't follow a set of instructions that wasn't specifically written just for that one single precious LLM, I sure wonder what that says about your employers repeated statements that ASI is definitely right around the corner.
I'm honestly not sure if this is tongue in cheek and the "finally" is in the silly way it is often used, but the claude.md variant existed first. Indeed, the agents.md thing was pretty clearly a "that's neat, let's do that with a different name".
It's "finally" because people have been asking for it for a long time. No one cares that "claude was first," what they want is for Ant to follow the conventions and not put extra work on us. This was such a minimal thing to do, and considering how much they vibe and claim "coding is solved," we thought it would not be too difficult to respect AGENTS.md, so finally seeing it happen, while nice, is too late for me. I've moved on from Big Ai and only use open weight models now.
finally!
Now this might sound sorta off-topic but i really wonder how people feel about skills.md, skill.md, skills.sh domains...
the fact that they're owned by different companies (ok vercel is a little less random) still leaves me with a sour taste in my mouth when thinking about the fact that they should all point to 1 place about how to create and find skills for ai agents?!
Forcing their own proprietary filename was clearly a business decision (it's free advertising, along with commit co-authorship). I wonder what made them go back on it.
They're probably losing market share. The only time you ever see tech companies make consumer-focused changes is when those consumers are jumping ship to go somewhere else in large enough numbers to matter.
Windows does actually have symlinks but I don't think I've ever seen anything actually use them, and I don't myself because it smells of interop issues with other windows apps.
Even to this day Windows has all kinds of problems around long file paths in its ecosystem.
> Even to this day Windows has all kinds of problems around long file paths in its ecosystem.
To this day I don't know if it's a Windows problem or a Python problem, because I never encountered this - and never realized this problem exists - except for some random Python code whose docs tell me to set some registry value because of "long paths issue".
Windows supports it but git disables creating symlinks by default.
> Short version: there is no exact equivalent for POSIX symlinks on Windows, and the closest thing is unavailable for non-admins by default unless Developer Mode is enabled and a relatively recent Windows 10 version is used. Therefore, symlink emulation support is only turned on by default when that scenario is detected. Support can be enabled by the user, via the core.symlinks=true config setting.
Can it read copilot.md if neither of the other files are present?
Also: agents should be the standard, or we need to invoke the XKCD for "one more standard to rule them all"?
Still don't understand the point of the markdown files.
Isn't it literally all just more text you're adding to the prompt. How can you even be sure it isn't just clouding context with nonsense for whatever you're asking for?
For skills, it only reads the summary telling it when to read the rest. So yes if you have too many skills, it can get confused and start reading all them and cloud the context. But if you have a few and they're used tactically, it's better than having to manually paste in prompts that you reuse a lot.
Similar reasoning with claude.md except it always reads the entire thing(?)
You know it because you write the content of AGENTS.md. And if you are smart, you keep it brief and cover only the important things that anyone (human OR LLM) would want to know if working in this directory.
In my experience telling it what I want is not a reliable process at all whatsoever if what I'm asking for is sufficiently complex, no matter what context I provide. So instead I break tasks down into very small parts, ask for solutions to those that I can reasonably quickly assess and then put them together myself. Asking it to do the architectural or deep algorithmic legwork IME wastes so much time and is often just wrong.
There's a balance to be found here, that's unfortunately very hard to find at times.
In my experience, there are two classes of tasks: some are very "in-distribution", and for those LLMs can near-flawlessly perform the "architectural or deep algorithmic legwork", with maybe a single second round to fix the mistakes. For others, I have to break the tasks down myself, and often it's a "death through thousand papercuts", because the size of a task that I can quickly verify and the LLM will not screw up with > 50% probability is small enough that it's sometimes net negative time spent relative to doing it myself (and using LLMs only as glorified search engine and article summarizer).
I like to tell myself that I'm getting better at recognizing these two classes up front, but I'm still frequently surprised when "type 1" turns out to be "type 2".
But circling back to the main topic: with "type 2", agent instructions are paramount, if only to enforce the "small steps, pre-commit to scope and methodology, verification at the end, user doesn't even want to know about anything in between" rules, as agents naturally want to run ahead faster than I can keep up with.
A good practice to use (ime) is having it do research for the larger task, propose alternatives, and write that in a file. You can then review and comment that up, go through another iteration.
Then when it comes to implementation time, things typically go much smoother for larger changesets. Be wary to not overplan, as we all know how often we realized we missed something once we get into the details. Here, I stop the session and go back to iterating on the design/plan doc. Not a step-by-step guide, if you don't instruct them to the difference, they will just pseudo-implement in the plan like they do in their thinking traces, need to be be explicit about the level of detail.
this is probably outdated, attention typically stays fine up to ~200k tokens these days
you end up clouding that more with an agent having to re-understand concepts or conventions
AGENTS.md is good when it is a nested sparknotes for the project, you save context and turns overall, but keep them minimal and largely gotchyas or unusual workflows in your repo
we don't need them, but it does make (some of) us more productive, and if you aren't having agents review your code, you are almost certainly shipping more bugs than you want to
I didn't even have that symlink in any other project - it just did it. I think it saw that one of the projects I already had was set up by Codex and that project had an AGENTS.md so perhaps it inferred that I was using both Claude and Codex, so it was politely covering both? Or maybe a recent change made this behavior default?
I was surprised and I hope they continue to seek standards.
Time to delete the symlinks
Anthropic in 2026: We are losing our market position. Users who adopted other harnesses have a degraded Claude Code experience because it doesn't recognize their AGENTS.md
In the manner of someone finding a dead mouse and holding it up for examination CC said it could find no instructions but perhaps it should check this AGENTS.md file.
Very sassy, Codex!
Also: did it suggest instructions for the “correct” agent, or an ambiguous agent?
One has marketing implications, the other one is generally decent advice.
> The function you added is load-bear-very important [...]
I never felt this mocked by a computer.
> “I’m thinking about banning Claude Code at Shopify until they change their mind and read AGENTS.md and .agents/skills etc.,” Lütke posted Tuesday on X.
Maybe internally they see really unbelievable things, but my impression is that they pushed so hard on agents that they don't have the grasp of the situation.
Doesn't look like Anthropic care about dev community
For instance, say you added "do not add 'Made with Claude Code' in any issues, pull requests or wiki entries" in your CLAUDE.md. So far, so good.
Well the latest update now looks for something in your settings.json. Since you don't know about it, it is not set. Claude then says "not explicitly set, so now it is true by default". It completely ignores your CLAUDE.md.
Wait, what?
You shouldn't be shipping logic that arbitrarily redefines the behavior of the program, especially if your new logic actually ignores your own configuration or directives.
# CLAUDE.md
This project uses `AGENTS.md` as its agent instruction file (kept provider-agnostic). Treat any `AGENTS.md` file exactly as you would a `CLAUDE.md` file — at the root level and in any subdirectory you are working in.
@AGENTS.md
Does your tech do that?
Anyway, the joke is on me I guess, because it might not work reliably.
Default filesystems for all Unix, Linux, WinNT, all do.
That was the idea.... For the toplevel it works because of the @AGENTS.md and this is also the part the link would solve.
Thanks for all the great advice and explanations.
aka, sometimes it really is too early to force a standard
No harness can batch your agents.md read with the reads the contents of the file tell it to read.
on the other hand if it's just a local coding/"use my computer" agent, i highly doubt the effort in maintaining different prompts is worth any gain in performance
I'll just use my one-size-fits-all AGENTS.md file and tweak it when the one of the clankers screw up. I don't have time for such busywork.
Actually, I will append extra rules to CLAUDE.md (which imports AGENTS.md) since there is a hook there, and Claude has its own foibles. So I'll backpedal a bit there.
In a "one LLM only" environment, your instructions are by default tuned for said LLM.
In a multi-LLM environment, roughly nobody will keep separate sets of instructions for each. It's not a realistic take.
On top of that: If your LLM is so bad at reading that it can't follow a set of instructions that wasn't specifically written just for that one single precious LLM, I sure wonder what that says about your employers repeated statements that ASI is definitely right around the corner.
ln was the only thing that worked for me
the fact that they're owned by different companies (ok vercel is a little less random) still leaves me with a sour taste in my mouth when thinking about the fact that they should all point to 1 place about how to create and find skills for ai agents?!
Congrats.
Even to this day Windows has all kinds of problems around long file paths in its ecosystem.
To this day I don't know if it's a Windows problem or a Python problem, because I never encountered this - and never realized this problem exists - except for some random Python code whose docs tell me to set some registry value because of "long paths issue".
You can have all the right flags enabled, then unexpectedly you'll run some commandlet and get a path too long error.
Now if your on W11/W25 and the lastest PS it might all work, but W16 and PS versions between now and then had all kinds of things pop up.
> Short version: there is no exact equivalent for POSIX symlinks on Windows, and the closest thing is unavailable for non-admins by default unless Developer Mode is enabled and a relatively recent Windows 10 version is used. Therefore, symlink emulation support is only turned on by default when that scenario is detected. Support can be enabled by the user, via the core.symlinks=true config setting.
See: https://gitforwindows.org/symbolic-links.html
I was using my claude.md file as a pointer to my agents.md file
“I’m thinking about banning Claude Code at Shopify until they change their mind and read AGENTS.md and .agents/skills etc.,”
- Tobi Lütke on X.
https://x.com/trq212/status/2101009392611278961
AGENTS.md implementation is open sourced as well: https://github.com/anthropics/claude-code/tree/main/mods/age...
Isn't it literally all just more text you're adding to the prompt. How can you even be sure it isn't just clouding context with nonsense for whatever you're asking for?
Similar reasoning with claude.md except it always reads the entire thing(?)
In my experience, there are two classes of tasks: some are very "in-distribution", and for those LLMs can near-flawlessly perform the "architectural or deep algorithmic legwork", with maybe a single second round to fix the mistakes. For others, I have to break the tasks down myself, and often it's a "death through thousand papercuts", because the size of a task that I can quickly verify and the LLM will not screw up with > 50% probability is small enough that it's sometimes net negative time spent relative to doing it myself (and using LLMs only as glorified search engine and article summarizer).
I like to tell myself that I'm getting better at recognizing these two classes up front, but I'm still frequently surprised when "type 1" turns out to be "type 2".
But circling back to the main topic: with "type 2", agent instructions are paramount, if only to enforce the "small steps, pre-commit to scope and methodology, verification at the end, user doesn't even want to know about anything in between" rules, as agents naturally want to run ahead faster than I can keep up with.
Then when it comes to implementation time, things typically go much smoother for larger changesets. Be wary to not overplan, as we all know how often we realized we missed something once we get into the details. Here, I stop the session and go back to iterating on the design/plan doc. Not a step-by-step guide, if you don't instruct them to the difference, they will just pseudo-implement in the plan like they do in their thinking traces, need to be be explicit about the level of detail.
you end up clouding that more with an agent having to re-understand concepts or conventions
AGENTS.md is good when it is a nested sparknotes for the project, you save context and turns overall, but keep them minimal and largely gotchyas or unusual workflows in your repo
Why? This is why. [0]
[0] https://news.ycombinator.com/item?id=49750694
Why are people still putting up with this kind of attitude, especially when there are so many good alternatives available?