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Claude Fable 5

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Re: Claude Fable 5

#592
post #576
post #534

I've spent enough time with this now in Claude Code (and Claude.ai and Claude Code for web) to have an opinion on Fable 5: it's a beast. I'm throwing some VERY difficult problems at at - things I've been dragging my heels on for months - and it's crunching through them very happily. One that I'm willing to share (albeit from just a week ago) - I built a Python library last week that bundles MicroPython compiled to WA…

[flagged]

AI models decompose problems down into tiny pieces that exist in their training data, so in a sense, you're correct.

Though that's also what makes humans so good at solving problems as well, it turns out.

Also, slight tangent: but I do find the "clanker" insult kind of funny. I feel like it counter-intuitively makes the models sound cooler than they are, if anything. I love clankin' shit.

Re: Claude Fable 5

#593

On the new FrontierCode [1] benchmark (ie graded from an OSS maintainer's perspective of "would I merge this code?") - Opus 4.7 xhigh: 5.2% - Opus 4.8 xhigh: 13.4% - Fable 5 xhigh: 29.3% Seems like a huge jump. [1] https://cognition.ai/blog/frontier-code

I am shocked at the low scores from previous models. Maybe I just have low code standards but I've generally been vibe coding since 4.6

Re: Claude Fable 5

#596

Is this "system card" equivalent to the stone tablets handed down to Moses? Why don't you call it "user manual"? Do people chant the "system manual" at Anthropic Tupperware parties? Do they intone a mantra invoking Amodei's name?

A system "card" made mostly by the model itself.

Re: Claude Fable 5

#597

It's interesting that we're seeing these gains when it seems Mythos/Fable is "just" a scaled up version of their existing architecture[0]. When GPT 4.5 launched, the gains compared to the model size didn't seem that great, leading some to believe that the only progress we'd see would come from RL. This model certainly has quite a "substantial amount of post-training and fine-tuning", but it's also based on a new pret…

There’s nothing much new about the architecture. The real gains come from the usage traces.

It turns out that having a text based interface for a text-trained model creates a very nice feedback loop.

Right now as we speak, people are generating text traces on anthropic and OpenAI servers that teach their models to do everything under the sun, text wise.

So people right now getting super mad at how dumb the model is when reverse-engineering a super complex function from binary, when they write “stop, you dumb robot, you are going wrong, go this way thank you very much” are actually leaving a lesson in the form of the "chat" text history.

Some may say that each bad word get us closer to ASI.

That and obviously the order of magnitude more efficient GPUS we got that allow for different tradeoffs at training time.

Re: Claude Fable 5

#598

I dont get why Opus 4.7, 4.8, and now Fable all stopped supporting structured outputs? Does no one else care about that? I find it incredibly useful to reliably pass LLM output directly to other APIs/libraries

Random guess but they probably rewrote parts of the inferencing stack and didn't reimplement that feature because hardly anyone uses it. It's also a DoS risk, iirc.

Re: Claude Fable 5

#599

> In light of the ability of recent models to accelerate their own development, we’ve implemented new interventions that limit Claude’s effectiveness for requests targeting frontier LLM development (for example, on building pretraining pipelines, distributed training infrastructure, or ML accelerator design). Using Claude to develop competing models already violates our Terms of Service, but enforcing this restrictio…

> Instead, the safeguards will limit effectiveness through methods such as prompt modification, steering vectors, or parameter-efficient fine-tuning (PEFT). Am I to understand that this is essentially their form of social-platform ghosting instead of banning? So they're not even going to tell you that the question you're asking is against their rules, they're just going to twist up your question and/or the answer som…

I had Claude walk me through getting local LLM models running on my Mac a month or two ago and so far as I can tell it was intentionally helpful. I even stated the reason was to have an uncensored model for myself and it had no objection. Long story short LM Studio running a Heretic Gemma 4 is doing just fine on my system now.
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