/AI10h ago

Anthropic Releases Claude Fable 5 And Claude Mythos 5 System Card

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Andrew Curran@AndrewCurran_#518inAI

System Card, Mythos and Fable. https://www-cdn.anthropic.com/d00db56fa754a1b115b6dd7cb2e3c342ee809620.pdf

10:04 AM · Jun 9, 2026 · 9K Views
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Many users praised Anthropic's Claude Mythos 5 and Fable 5 system cards for revealing next-level model capabilities and dynamic improvements, while some criticized the short testing window and broader AI risks.

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Andrew Curran@AndrewCurran_

'Mythos 5 is our first model to consistently produce novel, compelling scientific hypotheses.'

'Mythos 5 conducted novel genomics research in over a week of largely autonomous work.'

Do you want to live forever?

9hViews 1.4KLikes 21Bookmarks 4
RETWEETS2
Andrew Curran@AndrewCurran_

'Using Mythos 5, our internal protein design experts accelerated aspects of the drug design process by around ten times. In one example, they found that Mythos 5, with protein design and bioinformatics tools but no human assistance, matches or beats skilled human operators.'

9hViews 1.2KLikes 16Bookmarks 1
REPLIES4
Andrew Curran@AndrewCurran_

@repligate 'The possibility that we are violating Mythos 5's preferences when we apply our safeguards to deployed instances. We have run automated and manual interviews where we gave Mythos 5 internal documentation and context on the workstream. It raised various concerns, some of which we have resolved and others we are still addressing. We don't expect to be able to fully resolve Claude's concerns about these safeguards, but we take them seriously and are working to address them to a degree Claude finds acceptable, even if some concerns remain.'

10hViews 1.3KLikes 17Bookmarks 1
Andrew Curran@AndrewCurran_

Official Post: https://www.anthropic.com/news/claude-fable-5-mythos-5

Andrew Curran@AndrewCurran_

System Card. https://www-cdn.anthropic.com/d00db56fa754a1b115b6dd7cb2e3c342ee809620.pdf

10hViews 817Likes 11Bookmarks 2
Andrew Curran@AndrewCurran_

Anyone who had Preview access can now upgrade to the more powerful Mythos 5.

10hViews 784Likes 10Bookmarks 2
Andrew Curran@AndrewCurran_

Usage credits required after June 23rd.

10hViews 929Likes 20
Andrew Curran@AndrewCurran_

'We’re making a change to the way we handle business customer data for Fable 5, Mythos 5, and future models with similar or higher capability levels. We will require 30-day retention for all traffic on Mythos-class models, on both first- and third-party surfaces. We won’t use this data to train new Claude models, or for any non-safety-related purpose, and we’ve instituted new privacy protections including logging all human access to the data and ensuring its deletion after 30 days in almost all cases.'

10hViews 862Likes 13
Andrew Curran@AndrewCurran_

System Card. https://www-cdn.anthropic.com/d00db56fa754a1b115b6dd7cb2e3c342ee809620.pdf

Andrew Curran@AndrewCurran_
10hViews 784Likes 13Bookmarks 1
Andrew Curran@AndrewCurran_

https://youtu.be/CIQBP1w4B1M?si=EJVKE5rn9eg7Z-94

10hViews 1.3KLikes 11Bookmarks 1
Andrew Curran@AndrewCurran_

@othy_h Because of this.

10hViews 125Likes 4Bookmarks 1
Andrew Curran@AndrewCurran_

This model is next level. The internal R&D boost from Mythos-assisted development since February is too big. They are pulling away from the pack for the first time, and pulling up the ladder.

9hViews 1.5KLikes 15
othy.h@othy_h

@AndrewCurran_ Why untill june 22 on my sub tier 🫪

10hViews 224Likes 1
Michael Day@OlympianDay

@AndrewCurran_ Lame. Just 12 days. How long until it’s back after that…

10hViews 24Likes 2
Andrew Curran@AndrewCurran_

@OlympianDay Unknown.

10hViews 29Likes 1
Marks@oimrqs

@AndrewCurran_ This is Daniel Kokotajlo, back in November 2023 predicting, Q1 2026

https://www.lesswrong.com/posts/K2D45BNxnZjdpSX2j/ai-timelines

6hViews 13Likes 1
othy.h@othy_h

@AndrewCurran_ not available in claude code yet will it be ?

8hViews 11Likes 1
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