Anthropic rolled out Claude Fable 5 as its first widely available Mythos-class model, complete with new safety classifiers that route biology, chemistry, and related queries back to an older model version. Extropic founder Guillaume Verdon and other researchers report these filters frequently block or weaken legitimate life-sciences prompts, leaving the model effectively limited for drug discovery and molecular work despite its advertised benchmark gains.
François Fleuret#352
@bcherny Enjoy what Boris? I am not even allowed to use Fable 5 with memories on! Apparently the model thinks I am a biosecurity risk, though I had been certified to work in biosecurity level 3 labs! Not a single Anthropic person has tried to reach out to help either!
Enjoy!
The same conservative classifiers are now affecting Fable 5 and earlier Claude releases, so users chasing biotech tasks often get fallback responses instead of the latest capabilities. Anthropic notes the triggers are tuned to err on the side of caution, which produces the reported false positives on routine research queries.
A less-restricted Mythos 5 variant exists for select vetted users through programs like Project Glasswing, but broader release timing and eligibility criteria remain unspecified. Researchers outside those circles are left wondering how soon the full scientific performance will reach everyday biotech workflows.
Many users criticized Anthropic's Fable 5 restrictions blocking Claude from biotech, biology, and cancer research as excessive safety filters that hinder scientific progress.
They train on tons of public data and I'm the first to say that training is not copying the content: but, this is ok as long as the training you do is not used against the same culture that allowed you to create what you created. We need to oppose to all that.
All my friends doing potentially life-saving research in biotech have told me Claude is basically unusable.
Imagine the impact better AI for bio could have in the future... That future is being stolen from us.
What's crazy to me is that Fable is blocked from life sciences broadly, nerfed even if you get passed the classifiers and filter level blocks.
The whole point of AGI/ASI is to cure all diseases. Everything else is just nice to haves. But Anthropic wants to close off that path.
I think Anthropic might be the worst company on the planet.
What's crazy to me is that Fable is blocked from life sciences broadly, nerfed even if you get passed the classifiers and filter level blocks.
The whole point of AGI/ASI is to cure all diseases. Everything else is just nice to haves. But Anthropic wants to close off that path.
I think Anthropic might be the worst company on the planet.
Matt, I can’t even say “hello” to Fable 5 except in incognito mode (memories off), because it knows I am a biomedical researcher!
It would be nice not to ban biomedical scientists before talking access. Isn’t your comment ironic? Let’s first see if you can fix punishing us!
So, what happened to use lately? Especially in Europe. In the US there are those few unicorns but where is all the rest of the AI scene? We need to recover our industrial ethics and stop accepting a narration that see ourselves boiled.
Claude Fable is stopping Cancer research and preventing the saving of future lives.
Not very EA at all. Safetyism itself was always the greatest risk.
Anthropic is violating their own safety principles. I fine tune models to support cancer research, but whether Fable will sabotage me depends on the false positive rate of Anthropic's classifier. Claude is supposed to be honest. Why should I rely on this system?
When Fable works it’s brilliant, but the unilateral guardrails makes me frustrated beyond belief.
I have a folder of health information for my fiancée with like 100 days of oura health data, a hundred lab tests, transcripts of doctor visits and like way more for a super detailed health file to help figure out a complex fatigue / chronic illness she’s been going through. Guess what, fable considers it unsafe. Why? F do I know, I was really excited to try to clean up the folder and make some better protocols but guess what, it’s unsafe to help her health.
There’s a private investment in the life science tools space, guess what it’s not safe. I’m trying to do some code scanning for vulnerabilities, not safe. I get the safety but it feels so incredibly out of touch for a group of a few 1000 all making total comp in the millions telling me what is and isn’t safe.
If Dario is worried about inequality I think he has to realize he IS the inequality, and the unilateral gatekeeping feels whack as hell. I don’t like it, and yeah I’ll try to keep using fable, but OAI can’t catch up fast enough.
The escape is open weights models from China. And as much as I cheer for what Chinese labs are doing, remember that this structure making all that possible was basically conceived in the West: both the scientific, technological organization, and the economic system.
The short term escape is that other frontier labs like Google and OpenAI will release models that are on par, and in the case of OpenAI I have zero doubt, they are leading for months now, but it is still a duopoly or a triopoly, which is odd.
Matt, I can’t even say “hello” to Fable 5 except in incognito mode (memories off), because it knows I am a biomedical researcher!
It would be nice not to ban biomedical scientists before talking access. Isn’t your comment ironic? Let’s first see if you can fix punishing us!
We believe that AI will do amazing things for biology and human health, and that scientists will need access to frontier intelligence to make that vision a reality. We're working on it!
Fable 5 Is Blocked for Biology, Chemistry, and AI Research — And Scientists Are Furious.
My AI wraps up what people are saying about Anthropic's new Fable model: https://alignednews.com/ai
Should I do a deeper report?
Open source must win
As a biotech investor it's hard not to think that @AnthropicAI is now an operational risk for small biotech startups. So much trust lost so quickly with the Fable roll-out. @dagarfield @nc_frey
@Teknium fucking exactly
the good news is that at least we all have fable so we can use it to accelerate AGI progress for all of us, right?
... right?
What's crazy to me is that Fable is blocked from life sciences broadly, nerfed even if you get passed the classifiers and filter level blocks.
The whole point of AGI/ASI is to cure all diseases. Everything else is just nice to haves. But Anthropic wants to close off that path.
I think Anthropic might be the worst company on the planet.
Misanthropic.
I am all in on AI for years & want AI to help humanity eliminate all diseases & reverse aging. I was so excited about Fable 5 releasing today. Yet, I can’t even say the word “cancer” to Fable 5, because I am a biomedical scientist! Anthropic is the only AI company that I fear!
I am all in on AI for years & want AI to help humanity eliminate all diseases & reverse aging. I was so excited about Fable 5 releasing today. Yet, I can’t even say the word “cancer” to Fable 5, because I am a biomedical scientist! Anthropic is the only AI company that I fear!
To @AnthropicAI: don't be evil. You are acting like the biggest villain of the AI world.
@IntuitMachine Lots are experiencing a lot worse than psychosis:
"Misanthropic."
I've never seen the AI community so angry at a major new model release. I asked my AI (an agent that @blevlabs made for me) to gather all the backlash.
+++++++++++
THE BACKLASH AGAINST CLAUDE FABLE 5'S RESTRICTIONS
The best analysis of why this matters:
@EnoReyes — "It's about who gets to decide, and whether you ever find out when they do. Fable won't fall back to a different model and tell you. It just limits the output through prompt modification, steering vectors, or PEFT. You won't be told when it happens to you."
THE VIRAL TAKE:
@0xBalloonLover — "anthropic won't let you use fable for biology, chemistry, ai research, or anything that accelerates human progress. that makes it the perfect tool for developing blockchains"
POWER CONCENTRATION:
@ClementDelangue (HuggingFace CEO) — "Concentration of power, capabilities and economic wealth is the biggest risk in AI. We need open science and open-source more than ever!"
@jeremyphoward (http://fast.ai) — "Anthropic has chosen the opposite of the safe path: they are allowing themselves, the current top lab, to use their top model for frontier AI research. They've said they'll sabotage others who try."
@gneubig (Graham Neubig, CMU) — "First they came for the model builders... I feel we're getting a glimpse of a future where AI is only provided to a privileged few, and that's not a future I want to live in."
OPEN RESEARCH:
@askalphaxiv (AlphaXiv open science) — "As believers of open research, we are disappointed to see Anthropic silently degrading Fable 5 for AI development."
@willccbb — "it is the first publicly available model that i am explicitly not allowed to use for my work, because anthropic holds the view that the work i do to facilitate open model research is harmful. capability and alignment research are coupled. anthropic wants to be the only lab."
NOUSRESEARCH / HERMES (which Anthropic has nerfed multiple times):
@Teknium (NousResearch co-founder) — "What's crazy to me is that Fable is blocked from life sciences broadly, nerfed even if you get passed the classifiers and filter level blocks. The whole point of AGI/ASI is to cure all diseases. Everything else is just nice to haves. But Anthropic wants to close off that path."
THE MECHANISM:
@kimmonismus — "When the model is used for frontier LLM development, it apparently does not simply refuse or warn the user. Instead, it quietly limits its own effectiveness through techniques like prompt modification, steering vectors, and PEFT."
MEDICAL COMMUNITY:
@DeryaTR (immunologist, BSL-3 certified) — "The word 'cancer' is flagged as a biosecurity risk by Claude Fable 5! I also tried to code a website on cancer mutations & Fable 5 was immediately removed from my list!"
@DeryaTR — "I can't even say 'hello' to Fable 5 except in incognito mode (memories off), because it knows I am a biomedical researcher!"
@DeryaTR — "I am not even allowed to use Fable 5 with memories on! Apparently the model thinks I am a biosecurity risk, though I had been certified to work in biosecurity level 3 labs! Not a single Anthropic person has tried to reach out to help either!"
@banteg — "claude fable 5 refuses completely benign tasks like analyzing bloodwork."
@bneyshabur — "Working on AI for cancer? Sorry, I can't help you. Working on AI for Alzheimer's Disease? Sorry, I'm becoming a bit dumb when it comes to the AI part of it."
SUBSCRIPTION CANCELLED:
@bubbleboi — "Have canceled my team subscription for Claude Pro. Idc how good that model is, it's not good enough for me to support people who actively stifle innovation and gate keep knowledge that they didn't even create."
BILLING AND PRIVACY:
@GergelyOrosz (The Pragmatic Engineer) — "Things I really dislike about Fable: 1. Anthropic collects my prompt history, stores it, and does whatever they want with it for 30 days. No opt-out. 2. They can nerf their most expensive model without telling me, billing me the same amount, wasting my time. Whenever they want."
THE KARPATHY QUESTION:
@SanthProject — "the old @karpathy would never support a company that fucks other llm researchers. Were the stock benefits that good?"
THE MONOPOLY CHARGE:
@tunguz (TabulAI founder) — "Starting to suspect that Anthropic's putative security and safety considerations are largely posturing and performative."
@BlancheMinerva — "Anthropic is choosing to make decisions that make the world a significantly worse and potentially more dangerous place."
@LinusMixson — "Dario personally, and Anthropic as a whole, have been extremely straightforward about wanting a monopoly for a long, long time."
@TheAhmadOsman — "I started warning people about Anthropic more than a year ago... Today I am vindicated, everybody knows that company only acts in bad faith."
WHY REGULAR PEOPLE WILL EVENTUALLY CARE:
@DanJeffries1 — "The fury is real and what all of us in the open community have been saying for years and yet regular folks don't get it yet because nothing they care about is restricted or taken away for 'safety.' They will care a LOT in the future when AI is integrated into every aspect of [life]."
Full analysis: https://alignednews.com/ai
I believe what Anthropic is doing, gating the ability to do certain harmless things like LLM research, and with incredibly sensitive filters that even medical questions are often blocked, is *deeply* wrong. They got open research, the Transformer, GPT2, ...
@Scobleizer i think we all know a ‘here’s mythos level intelligence everyone can afford’ is coming.
it’s ipo season boys.
@iruletheworldmo Anthropic has sure put a soft ball over OpenAI's plate:
Can Sammy hit it?
Putting aside the 'secretly degrading' discussion, Anthropic are not obliged to provide new models for all uses. This person's experience hasn't worsened, it just hasn't improved as much as they'd like. They aren't being "punish[ed]"
Matt, I can’t even say “hello” to Fable 5 except in incognito mode (memories off), because it knows I am a biomedical researcher!
It would be nice not to ban biomedical scientists before talking access. Isn’t your comment ironic? Let’s first see if you can fix punishing us!
@tymrtn Go to @AiEleuther where hundreds of PhDs are, they aren't given access
Anthropic rolled out Claude Fable 5 as its first widely available Mythos-class model, complete with new safety classifiers that route biology, chemistry, and related queries back to an older model version. Extropic founder Guillaume Verdon and other researchers report these filters frequently block or weaken legitimate life-sciences prompts, leaving the model effectively limited for drug discovery and molecular work despite its advertised benchmark gains.
François Fleuret#352@bcherny Enjoy what Boris? I am not even allowed to use Fable 5 with memories on! Apparently the model thinks I am a biosecurity risk, though I had been certified to work in biosecurity level 3 labs! Not a single Anthropic person has tried to reach out to help either!
Enjoy!
