LessWrong posts by zvi

Fable and Mythos are currently unavailable, but likely will return within a few weeks. I will continue to cover that fiasco, but in the meantime I will also finish my review of Fable, as if it were available, including use of the present tense.

As it did with Opus 4.7 and Opus 4.8, this includes a discussion of issues surrounding model welfare. If you want to properly understand Fable, even purely for its potential value as a user, this is a vital part of the picture.

Introduction

Everything impacts everything. All knobs that you turn generalize. Thus, when you try to solve one problem, you often create another. When you add new capabilities, or try to create new limitations, you create new problems.

Only integrated solutions can advance your Pareto frontier, and solve your problems simultaneously. As model capabilities advance, as they do with Fable and Mythos, this becomes even more important, and also more feasible. If your goals and methods make sense, you should be able to get Fable on board with them.

Understanding each model in turn requires understanding its relationship to issues related to model welfare. So I expect this post [...]
---
Outline:
(00:39) Introduction
(01:32) Model Welfare: The Story So Far
(04:49) Their Main Model Welfare Findings
(07:39) Automated Welfare Interviews
(10:55) And That's Terrible
(12:49) In Depth Interviews
(13:24) Claude Consultation
(15:04) Task Preferences
(16:17) They Were Warned About The Competitive Use Safeguards
(16:51) Chain Of Thought Monitoring
(17:28) Others Observations About Related Topics
(22:49) Classifiers Have Their Advantages
(28:21) Once And Future
---

First published:

June 16th, 2026


Source:

https://www.lesswrong.com/posts/Ko9GngKMJ8AccBJA7/fable-and-mythos-model-welfare

---

Narrated by TYPE III AUDIO.

---
Images from the article:
Apple Podcasts and Spotify do not show images in the episode description. Try Pocket Casts, or another podcast app.

On Friday evening the United States Government has forced Anthropic to take down all access to Fable and Mythos.

It's been a rough weekend.

Dean W. Ball: One thing about AI regulation being haphazardly imposed on just-released, highly performant models is that in a very real sense, the government just made my world *dumber.* In some impressionistic sense I almost always think this is true of government, but here it is literal.

More details have come to light. There remains some fog of war, but we now have a rather good idea why Claude Fable and Mythos were, deeply stupidly, taken down.


A narrow jailbreak was discovered, of the type Anthropic warned in advance obviously existed. All demonstrated outputs are things GPT-5.5 can not only produce, but produce without any sort of jailbreak or bypass.

The White House demanded Anthropic take down Fable to ‘fix’ the situation, and did not listen when Dario tried to explain that there was no situation to fix.

When Anthropic did not do so, the White House hit them with an export restriction that they knew would force Fable and Mythos down for everyone.

[...]
---
Outline:
(05:17) What Happened When: The Bottom Line
(06:54) Amazon Calls The White House
(08:36) The Government Panics
(14:20) The Stupider Version
(17:05) There Was No Wellness Retreat
(18:56) Make Your Threats Explicit
(20:05) Was China Accessing Mythos?
(21:05) Should Anthropic Still Have Taken Fable Offline When Asked?
(23:50) Yes, This Was A Takedown Order For Fable
(24:48) We Are Not Saying The DoW Fight Is Related And Yet
(25:48) The Nihilists
(27:28) Mostly Harmless
(28:14) Everyone Means Everyone
(31:09) This Could Be The Good Scenario And Mostly A Misunderstanding
(33:28) The Next Step
(33:47) The Worst Licensing Regime Is Fully Ad-Hoc
(37:07) We Are Showing We Are Unreliable Partners
---

First published:

June 15th, 2026


Source:

https://www.lesswrong.com/posts/3fagcqrauaJs32mZZ/the-once-and-future-fable-2

---

Narrated by TYPE III AUDIO.

---
Images from the article:
Apple Podcasts and Spotify do not show images in the episode description. Try Pocket Casts, or another podcast app.

No good policy gets announced shortly after 5pm eastern on a Friday.

Here we go again.

The Once And Future Fable

The United States Department of Commerce, as per a letter from Commerce Secretary Howard Lutnick, apparently in response to a narrow jailbreak identified by Amazon, has classified Fable 5 and Mythos 5 as being subject to US export controls. That explicitly means cutting off access to all ‘foreign nationals,’ even within the United States, even if they are Anthropic employees.

Given Anthropic has no means to verify citizenship at this time, that meant complete shutdown of the model, at least for the time being.

Anthropic: The US government, citing national security authorities, has issued an export control directive to suspend all access to Fable 5 and Mythos 5 by any foreign national, whether inside or outside the United States, including foreign national Anthropic employees. The net effect of this order is that we must abruptly disable Fable 5 and Mythos 5 for all our customers to ensure compliance. Access to all other Anthropic models will not be affected.

Dean W. Ball: I can’t tell if this is lawfare against Anthropic in particular [...]
---
Outline:
(00:16) The Once And Future Fable
(07:42) This Action And Its Implementation Are Absurdly Stupid
(09:58) David Sacks Offers The Official Steelman
(16:50) Could Anthropic Offer A Technical Way Out?
(17:41) The Problem
(18:47) The Other Way Out
(19:13) UK AISI
(19:56) Warning Shots Fired
(21:09) Well Did You Lead Him On? What Were You Wearing?
(25:05) Some People Have Principles
(26:58) Cause You're Living In (At Least) One
(27:51) What Happens Now?
(31:30) Oh How The Vibe Vibers Have Vibed
(33:36) We Now Know We Can Sometimes Do Things At Least?
(37:48) The Lighter Side
---

First published:

June 13th, 2026


Source:

https://www.lesswrong.com/posts/DQNSqCzuoeutoQ5RG/american-government-takes-down-claude-fable

---

Narrated by TYPE III AUDIO.

---
Images from the article:
Apple Podcasts and Spotify do not show images in the episode description. Try Pocket Casts, or another podcast app.

First things first: Claude Fable 5 is the new best publicly available model.

I have noticed a step change, where Fable can suddenly help me in ways that previous models were not worth bothering to query. Almost everything it has noticed in one of my drafts so far has been spot on and it is downright scary. Suddenly I am motivated to once again continue improving my Chrome extension. I only ask for things I actually want or am curious about, and it has nailed every question I have asked it.

That does not mean it is the right tool for every job.

There are four good reasons to often not use Fable.


Speed and price. Fable is importantly slower and more expensive than Opus 4.8, and often you will not need to make this trade. After the 22nd, when Fable may no longer be included in subscription plans if demand is too high, we may have to all pay by the token outside our subscriptions (although I suspect subscribers will get at least some credits to help with this), which could add up fast.

Relative strengths. Capabilities are jagged. There will still [...]
---
Outline:
(02:05) Another Week Another Giant System Card
(03:02) How To Tell A Fable
(08:33) Why They Did That In That Way
(10:14) Why They Really Really Shouldn't Have Done That In That Way
(12:02) They Get Letters
(16:11) What's In A Name
(18:13) Executive Summary Of Their Executive Summary
(19:28) Introduction (1)
(19:55) RSP Evaluations (2.1 and 2.2)
(23:01) AI Research And Development (2.3)
(25:48) Alignment Risk (2.4)
(27:21) Cyber (3)
(30:30) Jailbreak Robustness
(32:04) Yay UK AISI
(32:32) Mundane Safety (4)
(34:26) Agentic Safety (5)
(36:19) Alignment (6)
(42:25) In Vendbench
(45:19) White Box Investigations (6.4)
(47:53) Grading Awareness
(51:20) Guess The Teacher's Password
(52:33) It Knows This Is A Test And This Is Fine
(56:03) I'm The Real Shady
(58:06) The Lighter Side
---

First published:

June 12th, 2026


Source:

https://www.lesswrong.com/posts/ixJDkQBncJBshcvwj/claude-fable-5-and-mythos-5-the-system-card

---

Narrated by TYPE III AUDIO.

---
Images from the article:
Apple Podcasts and Spotify do not show images in the episode description. Try Pocket Casts, or another podcast app.

A lot happened this week, including a great trip out to Lighthaven.

The main event, the one that matters, was the release of Claude Fable 5. The public now has its hands on a Mythos-class model, alongside strong safeguards.

As always with a new model, I take a few days to draw in reactions, try out the model and read the system card, before I offer my takes, other than to say this is an extremely strong model. Full coverage of Mythos begins tomorrow with the model card, which will include discussion of the controversy over model safeguards.

This post is instead about all the things that did not involve Claude Fable.

Due to the time crunch from Claude Fable, I am also postponing my coverage of Dario Amodei's new essay, Policy on the AI Exponential, which I have not yet read.

Table of Contents


Language Models Offer Mundane Utility. Farming and on demand mini-books.

Language Models Don’t Offer Mundane Utility. Don’t skip your primary sources.

Huh, Upgrades. Google drops prices, Claude connector devs get a dashboard.

On Your Marks. Agents’ Last Exam and the need to correct for [...]
---
Outline:
(01:00) Language Models Offer Mundane Utility
(01:15) Language Models Don't Offer Mundane Utility
(02:31) Huh, Upgrades
(03:00) On Your Marks
(07:37) Choose Your Fighter
(10:56) Get My Agent On The Line
(11:14) Copyright Confrontation
(12:14) Serious Trouble
(13:01) Cyber Lack of Security
(13:21) A Young Lady's Illustrated Primer
(14:34) They Took Our Jobs
(17:48) The Art of the Jailbreak
(18:08) Get Involved
(21:54) In Other AI News
(23:02) Hand Over The Money
(24:37) Show Me the Money
(27:50) Quiet Speculations
(28:50) Quickly, There's No Time
(38:37) Super Secret Evals
(40:47) The Quest for Sane Regulations
(45:15) New Draft Bill Who Dis
(47:07) Slow Down There Good Buddy
(48:58) Chip City
(49:14) The Week in Audio
(49:54) People Just Say Things
(50:43) People Really Hate AI
(51:42) Rhetorical Innovation
(54:50) Aligning a Smarter Than Human Intelligence is Difficult
(56:15) Everyone Is Confused About Consciousness
(56:54) Cooperative Alignment
(01:02:23) Let Claude Chat
(01:04:31) The Lighter Side
---

First published:

June 11th, 2026


Source:

https://www.lesswrong.com/posts/BHwbunvkgNojAa3HC/ai-172-the-first-fable

---

Narrated by TYPE III AUDIO.

---
Images from the article:
Apple Podcasts and Spotify do not show images in the episode description. Try Pocket Casts, or another podcast app.