Claude Fable 5.2 and Mythos 5.2

shmoil

>> Fable 5.2 and Mythos 5.2 are a step above Opus 5.5 in almost all the capabilities we evaluated. Was this before you lobotomized Opus 5.5 or after? https://news.ycombinator.com/item?id=50419019

minimaxir

There were more than a few "leaks" saying it would be called Fable 5.5, so I'm curious if a) the leaks were just engagementbait or b) Anthropic changed it, despite the fact that Fable 5.2 being better than Opus 5.5 is confusing. Surprisingly the model is available immediately in my Claude Code: usually there's a delay, either for rollout or safety.

iammrpayments

Too expensive for me

hmate9

Its cheaper at $8 per million input tokens and $40 per million output tokens which is also pretty sweet.

__natty__

Maybe it's just me, but I found Claude's writing style terrible compared to GPT or Gemini. It's "smart", but the way it communicates seems somehow off compared to other models.

ealready_value

Very interesting that they set the flagship's version number to 5.2, but their penultimate model is 5.5. Do they want people to to continue to think that Opus is based on more advanced technology? The decision these AI companies make continues to baffle me.

iamdelirium

FrontierCode 2.0 is such a poor benchmark for Gemini since it's the only model forced to use Devin CLI while other models get to use their preferred harness. I wonder why that team singles Gemini out like that.

aurareturn

Is this the Model 4 internal name? Reference: https://x.com/METR_Evals/status/2118412205662314935

tiffanyh

I didn't realize that Opus 5.5 was more capable than Fable 5.1 in virtually every category.

cobri

Does this coincide with the claimed nerfing of Opus 5.5? https://news.ycombinator.com/item?id=50422069

pookieinc

“Testers have found that Fable 5.2 and Mythos 5.2 communicate more clearly than past Fable and Mythos models. They generate outputs up to 30% faster than Claude Fable 5.1 and Claude Mythos 5.1, and they’re available at a lower price: $8 per million input tokens and $40 per million output tokens.” Honestly incredible that they’ve managed to beat all benchmarks, while making it cheaper. Always happy to see improvements offered at lower costs. Will be interesting to see what OpenAI does in response

canadiantim

god bless token resets!

awongh

Doubling Remote Labor Index (RLI) - at 41.3% compared to around 20% for the other models - I wonder what kinds of new agentic work this is going to unlock.

bananaflag

Those theoretical physics papers look like the real thing (i.e. not mathematical physics like the OpenAI Yang-Mills result). It looks like AI is finally branching out of math.

unshavedyak

Looks like some plans get extra fable usage: https://support.claude.com/en/articles/17506494-claude-fable...

artisin

We'll see what my bank account has to say about this: > Fable 5.2 at High effort scored about level with Opus 5.5 at Max effort, for roughly half the cost per task

mikert89

The end of software is so close, very soon the code itself will be nearly obsolete, there will be schedulers, queues, a database, and the model

skeledrew

Damn people were right about 5.5 being nerfed in preparation for a version release. This is not at all a good look. - https://news.ycombinator.com/item?id=50422069

butler14

Just read the other thread about opus being nerfed and thought "cue the new release"... paha

I_am_tiberius

It's pretty sad that they obviously have better models in the pipeline and don't release them yet for strategic reasons.