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Claude Fable 5.1 and Claude Mythos 5.1

anthropic.com

641–650 of 1001 posts

Re: Claude Fable 5.1 and Claude Mythos 5.1

#642

(I work at Anthropic) Beyond all the benchmarks, I think Fable 5.1 is a big improvement in writing style. It sounds a lot less stereotypically like other Claude models, has (imho) a much more natural style, and responds to my style instructions more reliably. More work to be done (and we will!) but reading better prose makes me so much happier. Another point I expect not to get much attention until it all happens at…

Does it fix my favorite pet peeve, the overuse of the wrong meaning of "fail closed"? "Fail open" usually refers to a fuse that opens and kills power, meaning the system is inert and safe on failure. "Fail closed" is the opposite -- system has power and is live. Computer security people have appropriated the term but use it for the completely opposite meaning. When your work straddles electrical engineering and compu…

I noticed Claude Opus 5 did this about 30 minutes after reading your comment. In a discussion of price feeds that have gone silent, Opus said - program should fail closed. I don’t want my circuits operating without data!

Re: Claude Fable 5.1 and Claude Mythos 5.1

#644
post #144

Pelicans for thinking effort low, medium, high and xhigh (that xhigh one is pretty good): https://tools.simonwillison.net/markdown-svg-renderer#url=ht... I'm still waiting for effort max to finish. EDIT: I fixed a bug in my tooling so it now records summarized reasoning traces - here's that max pelican, which is a significant improvement: https://tools.simonwillison.net/markdown-svg-renderer#url=ht... Took just under…

What’s the token usage of xhigh?

Re: Claude Fable 5.1 and Claude Mythos 5.1

#645

Unless these people start offering free, unlimited inference for a cautionary period so we can test the new model without an up-front (re-)investment, I am not touching this load-bearing pile of neuralese spew with a ten thousand token pole.-

Are you going to post the same comment on every AI article on HN? How is this useful to the discussion?

Re: Claude Fable 5.1 and Claude Mythos 5.1

#646

(I work at Anthropic) Beyond all the benchmarks, I think Fable 5.1 is a big improvement in writing style. It sounds a lot less stereotypically like other Claude models, has (imho) a much more natural style, and responds to my style instructions more reliably. More work to be done (and we will!) but reading better prose makes me so much happier. Another point I expect not to get much attention until it all happens at…

I have a pet theory that the Opus prose style/smell we all have grown weary of is due at least in part to the models writing more for themselves and each other than for humans. They're packing lots of signal into fewer words and they don't care if it sounds cringe because it works better as glue in long-running tasks. I'm also thinking of the 2017 novel "Void Star" where AIs who operate everything have long since lef…

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Re: Claude Fable 5.1 and Claude Mythos 5.1

#647

Am I alone in not prioritizing the quality of prose produced by my coding agent? My foremost and almost only concern is how well it can engineer software.

People love to complain, particularly if being anti-AI is a big part of their identity.

Re: Claude Fable 5.1 and Claude Mythos 5.1

#649
post #46

Looks like all three breaking changes are patches for inadvertent chain of thought disclosure. Someone found out (don't have the tweet handy) that if you created a bogus "think_deeply" tool and then forced the model to use it, it would output what is believed to be its raw thinking there - I believe the first breaking change stops this. The second two are aimed at people getting Haiku to repeat thinking blocks from o…

To be fair, I assume they want to hide that not from their customers, but adversaries who use the way Claude models think and reason to refine their own models.

That's their motivation, for sure. But it's also unambiguously making their product worse and harder to use legitimately. Which pushes customers further towards use of open weight models which don't have these restrictions. I don't think this is a fight they're going to win.

It's also hard to have sympathy for them - they want to protect their IP, sure. But their IP was built on a corpus of dubious legal provenance. And even if the courts decide their training data are legal, most of the authors of the data would disagree. There was no consent given.

I think LLM's are great - don't get me wrong. I'm glad they were built the way they were, because it's unlocking an amazing new world. But I just don't have sympathy for the "I stole this and now it's mine so you can't steal it" argument behind concealing reasoning traces.

Re: Claude Fable 5.1 and Claude Mythos 5.1

#650
post #552
post #510

Earlier quoted context omitted.

What do you mean fable is useless?

(not op) It cannot be used to develop applications. Every application needs to be secure in some way, and any such mention in a review triggers Fable's upsell feature.

Weird. I'm using it to do a bunch of work on something that manages security rules, with a bunch of sample data with spooky scary fixtures all over with "Mimikatz" and "CobaltStrike Beacon" and "Crowdstrike EDR" type stuff everywhere, including work to harden my system, and I've never been downgraded.
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