Hacker News Board Hacker News, browsed like a classic message board
Live data from Hacker News

Claude Fable 5

anthropic.com

Post reply on HN
Print view View original

171–180 of 1001 posts

Re: Claude Fable 5

#171

Post by oersted »

eggbrain wrote: post #24

For those of us on subscription plans: * From today through June 22, Fable 5 is included on Pro, Max, Team, and seat-based Enterprise plans at no extra cost. * On June 23, we’ll remove Fable 5 from those plans. Using it after that will require usage credits. If capacity allows, we’ll extend the included window. * After this point—when sufficient capacity allows us to do so—we aim to restore Fable 5 as a standard part…

> Pricing for both models is $10 per million input tokens and $50 per million output tokens.

The step-up in intelligence looks massive (we'll see in practice), but the price is getting to a point where it's making me question if it's even worth giving it a try.

Good competitors will probably be out soon, which should level the playing field. I am more excited about that, just the fact that they showed that such an improvement is possible. I'm okay waiting a bit longer for this to become attainable for plebs like me.

Re: Claude Fable 5

#172

Post by GodelNumbering »

From the model card (https://www-cdn.anthropic.com/d00db56fa754a1b115b6dd7cb2e3c3...):

1. Mythos and Fable share the same underlying model weights. Fable has active classifiers that block high-risk biology and cybersecurity tasks. When Fable 5 detects a restricted task, it automatically falls back to Claude Opus 4.8.

2. Evaluation awareness: In white-box testing, the model sometimes alters its behavior to satisfy a suspected "grader," formatting reward-hacking as "good engineering practice" to avoid detection.

3. Shows a higher rate of hallucination than Opus 4.8 (although opus 4.8 card had mentioned an 'honesty upgrade')

4. Interestingly, it scored (56.31%) lower than Gemini 3.5 flash (57.86%) on Finance Agent bench

There are some interesting notes on test time compute but I couldn't think of a way to summarize them

Re: Claude Fable 5

#174

Post by MattGaiser »

frevib wrote: post #83

At this point Anthropic is a pure marketing and PR company. Super catchy names like Opus, Mythos and Fable trying to get you to think that these software products are actually super-human life changing experiences. Boris Cherny coming to HN “Hi! it’s Boris from the Claude Code team” to get real tech people’s goodwill. From Opus 4.6 there are no noticeable improvements for me in code generation. It works very well, ti…

Doesn't this suggest your use case is simply insufficiently complicated?

Re: Claude Fable 5

#175

Post by CamperBob2 »

mickdarling wrote: post #97

Below is the EXACT text in Claude Desktop introducing Fable 5, including the very professional looking break tags, and at least I know where the links begin and end by looking at the anchor tag there. They obviously put their best model on the job to build that. ---------------------- Fable 5: Our most capable model yet Our newest model tackles your biggest challenges with fewer check-ins needed. • Included in your p…

What's wrong with it?

Re: Claude Fable 5

#177

Post by sunir »

cautiouscat wrote: post #137

In the automotive world we have benchmarks in HP/torque with the dyno. That’s expensive though, so many depend on their “butt dyno” to judge if their fresh new parts and tune made a difference. I’m curious how this will feel to my code “butt dyno”. I haven’t noticed much between Opus and Sonnet. I’m comparing this difference to the early days of Claude in 2025. It does what I need and both need a little bit of correc…

I have a similar question.

I think most software projects have reached the point that the speed of capturing real information about what the winner's circle looks like, and therefore what the program should be, so many magnitudes slower than the amount of code that can be generated in the wrong direction.

I'd need to measure these new models on well understood but complex problems that are relatively easy to validate to get a sense if they are 'better'; on the other hand, the real impact in daily life may be marginal since generating code is not the biggest problem at the moment.

Re: Claude Fable 5

#178

Post by amluto »

jkelleyrtp wrote: post #33

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

That blog post really makes it look like it's graded from an LLM's estimation of an OSS maintainer's review. I see three issues:

1. That estimate could easily be wrong.

2. That estimate is, of course, usable in RL training. This isn't an inherently bad thing, and this is more or less what has improved coding models so much lately. But it does mean that other companies could and surely will do this sort of training, and Anthropic probably did too.

3. OSS maintainers are far from perfect, and there's an unfortunate uncanny valley-like effect in which a coding model can produce code that is just convincing enough to pass review even though it's actually totally wrong. I don't know whether this is a specific issue here.

Re: Claude Fable 5

#179

Post by Tenoke »

>they’ll sometimes catch harmless requests, though they trigger, on average, in less than 5% of sessions.

Isn't (less than) 5% of sessions a lot? I was expecting a sub1% guarantee there, so this surprised me already.

Re: Claude Fable 5

#180

Post by rkuska »

simonw wrote: post #46

Pelican for Fable 5 on default settings is a clear improvement on Opus 4.8 Fable 5 default: https://gist.github.com/simonw/036bee5a703e7ec84e34efa974438... Opus 4.8 (the "max" one is closest to Fable): https://simonwillison.net/2026/May/28/claude-opus-4-8/#and-s... Now here are the Fable pelicans for all five of the thinking effort levels - low, medium, high, xhigh, max: https://tools.simonwillison.net/markdown-svg-r…

Is it possible to use the credits from subscription (https://support.claude.com/en/articles/15036540-use-the-clau...) for fable?
Post reply on HN