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Claude Fable 5.1 and Claude Mythos 5.1

anthropic.com

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Re: Claude Fable 5.1 and Claude Mythos 5.1

#301

Post by adastra22 »

felixrieseberg wrote: post #69

(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…

As someone working in science, this belief confuses me. How (by what means) do you think Fable 5.1 will be able to make further progress in scientific domains? The problem with science is that there is no agentic harness. The agent can't test things. At best it can hallucinate something and ask if that hallucination "makes sense", but this doesn't work in science.

Re: Claude Fable 5.1 and Claude Mythos 5.1

#302

Post by MassiveOwl »

felixrieseberg wrote: post #69

(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…

Thanks! This is encouraging. I try to use Claude Code for producing client facing presentations that are static html files with charts, tables, and annotations. It never gets the tone correct and phrases things so weirdly - it drives me mad. I have to really fight it to stop it writing insights in a flowery and verbose way

Re: Claude Fable 5.1 and Claude Mythos 5.1

#304

Post by simonw »

swalsh wrote: post #248
simonw wrote: 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…

Now that it's a solved benchmark, can we get the animated version?

I didn't want to shell out for Max again, so I piped the SVG created by Max back into Fable 5.1 at its default thinking level (of high):

  llm logs -cx | llm -m claude-fable-5.1 -s 'animate this'
Here's the result, which cost $1.37: https://tools.simonwillison.net/markdown-svg-renderer?url=ht...

It's excellent!

Re: Claude Fable 5.1 and Claude Mythos 5.1

#305

Post by sixhobbits »

caconym_ wrote: post #255

> We’re introducing Claude Fable 5.1 and Claude Mythos 5.1. They’re the world’s most advanced models for coding and knowledge work—and their research capabilities offer an early glimpse of how AI models will contribute to scientific progress. I'm not an emdash hater but this isn't how you use them. It should be a comma.

Grammatically an emdash is fine in most places a comma is fine. It adds a bit more emphasis to the bit after the dash.

I went to the grocery store, and bought tomatoes.

I went to the grocery store---and bought a Ferrari.

The second one has a bit more of a dramatic pause.

"Eats, Shoots, and Leaves" is a fun book with a great chapter about the dash with many good examples.

Re: Claude Fable 5.1 and Claude Mythos 5.1

#306

Post by droidjj »

caconym_ wrote: post #255

> We’re introducing Claude Fable 5.1 and Claude Mythos 5.1. They’re the world’s most advanced models for coding and knowledge work—and their research capabilities offer an early glimpse of how AI models will contribute to scientific progress. I'm not an emdash hater but this isn't how you use them. It should be a comma.

Em dashes are commonly used to add emphasis, even where you would ordinarily use a comma. Their flexibility is why many people love them! See https://www.merriam-webster.com/grammar/em-dash-en-dash-how-...

Re: Claude Fable 5.1 and Claude Mythos 5.1

#307

Post by dboon »

keeganpoppen wrote: post #296
dboon wrote: post #197

I've been building Cargo-for-C ( https://github.com/tspader/spn ), and the difference between Fable and Opus was already astounding. Fable was the first time that I could point a model at a piece of code I'd written and expect it to make it meaningfully better rather than a hard pattern match to whatever mistakes it had. 5.1 so far seems like another leap, which is really surprising. I threw it at a few bigger featur…

i think we will all look back on Fable as the start of the AGI inflection point. for all i know there are still multiple leaps between now and AGI (i personally am inclined to think that for all intents and purposes we are "already there", but reasonable people can still disagree on that point), but Fable was the first time that something felt genuinely magical about the results themselves, not just particular output…

Yeah, I agree. The first time something felt magical about the results themselves. That's it!

Re: Claude Fable 5.1 and Claude Mythos 5.1

#308

Post by EliasWatson »

To be honest, these frontier model releases have become boring for me. Opus 4.8 was already good enough for most of my use cases. I don't have any projects right now that I would use Fable for instead of Opus. So when I see announcements like this I just think "that's cool I guess" and then go back to using weaker/cheaper models.

What's far more exciting right now is models like DeepSeek V4 Flash and GLM 5.3 Flash. They have achieved good-enough-intelligence at extremely low prices and fast speeds. I don't have a use for Fable-level intelligence, but I do have uses for Opus-4.8-level intelligence that I can use as much as I want without worrying about the bill.

Re: Claude Fable 5.1 and Claude Mythos 5.1

#309

Post by efficax »

exabrial wrote: post #270
jumploops wrote: post #70

> For example, in testing by the investment firm Millennium, Fable 5.1 found the cause of a rare crash on their internal systems that none of their engineers (or any other model) had been able to explain after several years of trying. Say what you will about LLM-generated code, but stories like this give me hope that software will never be as buggy as it once was.

The marketing here trick is, if they spent the same money on humans they'd have found it years ago. Instead, the lurking variable here is new budget was added. With the new budget, they added a new tool, and the bug was located. The difference here was budget.

the budget for allowing a single engineer to deep dive on a bug that is annoying but also not bad enough that you can live with it for years is pretty big. $10k a month or more. My budget for Claude is $200/mo.

Re: Claude Fable 5.1 and Claude Mythos 5.1

#310

Post by Waterluvian »

felixrieseberg wrote: post #69

(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…

How much of the language style outcome is a well-crafted result vs. being a somewhat unpredictable outcome of mucking with levers and knobs for a while?
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