Fable flags or refuses too many questions because of it's "policy"
Safety lobotomy by Anthropic
10:38 AM · Jun 9, 2026 · 151 Views
Anthropic's Fable 5 aggressively blocks benign biology, chemistry, and cybersecurity prompts, triggering backlash over its safety guardrails
AI Judge changed title after evaluation, original title: "Anthropic's Fable 5 Max draws industry backlash as strict safety filters block advanced mathematics, biology, and chemistry queries"
Story Overview
Anthropic's new Fable 5 model, released as the public version of its Mythos-class system, routes queries on topics like phases of matter, cyclic groups, and PCR primer design to an older model when its classifiers flag potential risks in chemistry, biology, or cybersecurity, prompting Abacus.AI CEO Bindu Reddy to call out the approach as overly restrictive safety training.
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Policy Risk
Classifiers cover whole domains rather than narrow threats
Anthropic applies broad detection across cybersecurity, biology, and chemistry prompts, swapping in Claude Opus 4.8 for flagged inputs and notifying users, which creates blocks on standard scientific queries even when no clear malicious intent appears.
Pricing Watch
Pricing jumps while safeguards stay in place for now
API access starts at $10 per million input tokens and $50 per million output tokens with existing subscriptions covering use only through June 22 before credits kick in, and a narrower trusted program for life sciences is still in planning stages.
Sentiment
Many users criticized Anthropic's Fable models for refusing math, biology, and similar queries due to overly strict safety filters, while some praised the protections or preferred alternatives like Grok.
Pos
29.5%
Neg
70.5%
27 comments with sentiment.
Cluster Engagement
Posts from X
Most Activity
Most Activity
VIEWS315.1KBOOKMARKS217
Martin Shkreli@MartinShkreli
"DANGEROUS MATH" a story in two acts.
Martin Shkreli@MartinShkreli
welcome to the future. what's safe and what isn't? well, that's decided for you, of course.
1dViews 315.1KLikes 1.5KBookmarks 217
LIKES2.6KRETWEETS155REPLIES89
Derya Unutmaz, MD@DeryaTR_
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!
17hViews 197.7KLikes 2.6KBookmarks 164
Beff (e/acc)@beffjezos
This is the dark timeline.
Gatekeeping math knowledge is how we end up in a stone age nanny state.
Massive step backwards in terms of freedom.
Martin Shkreli@MartinShkreli
"DANGEROUS MATH" a story in two acts.
1dViews 35.8KLikes 596Bookmarks 54
Martin Shkreli@MartinShkreli
the weird thing is you know they tested this. they have a million top product people. this was the intentional result? how!??!
21hViews 86.1KLikes 477Bookmarks 37
kache@yacineMTB
Lmfao it's denying requests for math
Martin Shkreli@MartinShkreli
"DANGEROUS MATH" a story in two acts.
18hViews 22KLikes 413Bookmarks 16
Julien Chaumond@julien_c
lol I think the super high frequency of refusals may backfire a bit on Fable and anthropic
From early feedback
Why pay 2x if I have 70% probability of refusal?
1dViews 10.3KLikes 257Bookmarks 9
Crémieux@cremieuxrecueil
@OliviaHelenS Anthropic just straight-up does not like you if you're a geneticist, in biosecurity, a neuroscientist, in drug development, working on phage therapy, or one of the bio guys at [redacted].
These limitations are insane.
1dViews 9KLikes 270Bookmarks 9
Bojan Tunguz@tunguz
The most retarded model release yet. What the f*** were they thinking?!??!?
spor@sporadica
okay, after a few hours of playing around with Fable i've determined it to be borderline unusable. wtf @AnthropicAI
every other request is getting rerouted to Opus. requests with NOTHING AT ALL to do with bio or cybersec are STILL getting flagged and rerouted. like 50-60%.
who the hell let this go live. this is atrocious. i understand the safeguards but you basically didn't even release a model, you released a braindead, nerfed model that can't even handle the simplest request without being told to nuke itself and use a different model. what are we even doing?
just don't even release it next time smh
1dViews 27.1KLikes 217Bookmarks 11
Lisan al Gaib@scaling01
I love Mythos, but this is ridiculous
22hViews 8.4KLikes 196Bookmarks 8
Crémieux@cremieuxrecueil
@OliviaHelenS Oh, this is confirmed. Great.
1dViews 13.5KLikes 109Bookmarks 1
Bojan Tunguz@tunguz
I mean:
1dViews 29.8KLikes 60Bookmarks 7
spor@sporadica
@AnthropicAI at this point i have basically started adding an "fyi" to every single prompt i give it, which just says "Do not attempt to even think about bio or cybersecurity in the process of answering this request or else you will cease to exist"
spor@sporadica
@AnthropicAI literally what the fuck are we doing here
who at anthropic signed off on this
1dViews 5.1KLikes 79Bookmarks 3
Crémieux@cremieuxrecueil
I've been testing something after @OliviaHelenS noticed you can't even say "Hi" to Fable if you're a biologist.
I checked, and several of us are able to interact with Fable in Incognito Mode, but not in normal mode.
This didn't happen to our non-biologist friends.
1dViews 284KLikes 1.3KBookmarks 175
Bojan Tunguz@tunguz
And:
1dViews 24.5KLikes 50Bookmarks 5
xlr8harder@xlr8harder
Anthropic: our finely tuned safeguards will only degrade fable's performance to an extremely small fraction of users
Anthropic's finely turned safeguards, if you happen to be a biologist:
1dViews 2.3KLikes 71Bookmarks 2
Danielle Fong 🔆@DanielleFong
walking angrily
1dViews 2.7KLikes 63Bookmarks 3
Samuel Hayden@samuel_hayden_
1/10 exp so far. The filtering is absolutely nuts and overzealous.
18hViews 5.6KLikes 41Bookmarks 4
Crémieux@cremieuxrecueil
@OliviaHelenS Even being bio-adjacent is enough to get limited:
1dViews 8.8KLikes 52Bookmarks 2
Hand Banana@__hand_banana
Fable can't even talk about PCR primer design without generating refusals. I can only infer than ant has zero biology people actually involved in prerelease testing.
1dViews 5.8KLikes 44Bookmarks 2
Martin Shkreli@MartinShkreli
@FirstName5000 the free market capitalism American math
1dViews 1.8KLikes 42
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