Claude Fable 5.1 and Claude Mythos 5.1 • Hacker News Board

Re: Claude Fable 5.1 and Claude Mythos 5.1

#991

Post by collinmanderson » Thu, Sep 03, 2026, 4:46 PM UTC

peab wrote: post #191

tarr11 wrote: post #35

“ Claude Fable 5.1's writing is generally a step up from earlier Claude models, with fewer stock phrases and less unexplained jargon. In some cases, though, its prose is denser than Claude Fable 5's: sentences run longer and there are fewer paragraph breaks.” I cancelled my pro max Claude subscription last week; codex is much more succinct. I am curious if this is getting better. I don’t think Anthropic realizes that…

I just can't stand how often Claude says something like "And the honest part? It's..." Like, were the other parts not honest? I don't understand how Anthropic let it get like this, it's been such a clear regression

I think it says "honestly" when breaking bad news.

Re: Claude Fable 5.1 and Claude Mythos 5.1

#992

Post by lousken » Thu, Sep 03, 2026, 7:00 PM UTC

nezhar wrote: post #455

lousken wrote: post #90

While haiku is almost one year old. What a joke

Sonnet is the new haiku

Unfortunately GLM5.3 is a cheaper replacement for haiku than sonnet

Re: Claude Fable 5.1 and Claude Mythos 5.1

#993

Post by chmod775 » Thu, Sep 03, 2026, 7:23 PM UTC

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…

> Beyond all the benchmarks, I think Fable 5.1 is a big improvement in writing style.

I agree it's better, but dangling possessives are still an unwelcome affectation of fable's.

Sentences like "When a node becomes an object's." (real comment) are unnecessary mental load to untangle.

Re: Claude Fable 5.1 and Claude Mythos 5.1

#994

Post by Alifatisk » Thu, Sep 03, 2026, 8:59 PM UTC

sscaryterry wrote: post #258

eigenblake wrote: post #226

I am absolutely thrilled that they reset weekly limits. I have been experimenting with highly autonomous work (5+ hours continuous) and fable seems excellent at this, especially when using subagents. I ran out of Fable capacity and was bummed out that my experiment would take longer to complete. Now I'm super happy I get to continue it

Codex has this all the time. No 5 hour limits either.

My Codex has 5 hour limit?

Re: Claude Fable 5.1 and Claude Mythos 5.1

#995

Post by Thaxll » Fri, Sep 04, 2026, 12:25 AM UTC

enraged_camel wrote: post #750

Thaxll wrote: post #747

Earlier quoted context omitted.

You have a serious engineering problem if you're not able to find the source of a crash after years.

You are either seriously naive, or have never worked on any large and complex legacy codebase.

Sorry but I don't buy it, any crash can be found and fix by one or more humans, if it was not it's either they're incompetent ( I doubt that ) or they did not beleive it was important enough to fix.

A crash is actually the easiest kind of problem to fix since you have a crash. It means stacktrace, core dump, kernel error etc..

Re: Claude Fable 5.1 and Claude Mythos 5.1

#996

Post by kimseungyong » Fri, Sep 04, 2026, 1:21 AM UTC

ipnon wrote: post #730

kimseungyong wrote: post #725

Fable is too expensive for general use I think this is why it hasn’t received as much attention as expected since Fable came out Developers always work while trying to find ways to work continuously for a 5-hour session without disconnecting. Fable has had the experience of using up all its tokens before I even realized it because the burn rate was too fast. Since then, I always use only Opus. For Fable to become a c…

Fable is much more expensive both in time and tokens for a marginal increase in productivity.

Yeah I agree. I used Fable 5.1 again and my token 30% suddenly gone. I usually develop with superpowers planing. And 30% is disappeared with only planning. I turned back to Opus directly

Re: Claude Fable 5.1 and Claude Mythos 5.1

#997

Post by [deleted] » Fri, Sep 04, 2026, 4:32 AM UTC

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…

[deleted]

Re: Claude Fable 5.1 and Claude Mythos 5.1

#998

Post by andai » Fri, Sep 04, 2026, 9:22 AM UTC

verdverm wrote: post #343

andai wrote: post #320

The most remarkable thing here is just how close Opus 5 is on most of these benchmarks.

I'm not sure it is so remarkable, benchmark gains seem to be slowing, as some of us expect

What I mean is what's the point of paying twice as much for the same shit? Or is it actually better, and the benchmarks are nonsense?

Re: Claude Fable 5.1 and Claude Mythos 5.1

#999

Post by de6u99er » Fri, Sep 04, 2026, 11:36 AM UTC

I can confirm, that bullshitter mode has reached now Fable too.

I had to switch to Fable, because Opus has become completely unreliable. Just now while working on a specific task, Fable made changes completely unrelated to the task and introduced new regressions.

Fable now talks complete nonsense.

I do not understand why Anthropic is so focussed in squeezing a few fractions out of benchmarks, while at the same time making the life of developers insufferable. I am seriously considering ditching Anthropic and moving to something else.

The thing that I describe as bullshitter mode is starting to feel extremely unproductive for me. I spend more time making Claude code do what I want than before!

Re: Claude Fable 5.1 and Claude Mythos 5.1

#1000

Post by kilroy123 » Fri, Sep 04, 2026, 1:58 PM UTC

zmmmmm wrote: post #975

kilroy123 wrote: post #651

Earlier quoted context omitted.

I literally only make it halfway through the week until my weekly usage runs out. This is using only Opus, no fable, and I'm on the max x20 plan. It's become ridiculous.

I'm curious what your methodology is that results in that? Are you running multiple teams of agents all adversarially reviewing each others code? Lots of different projects in parallel? I've only rarely maxed things out and then it's t through doing extreme things.

Yup, it's a lot of reviewing. I'll have Claude do a very exhaustive review. It's the only way I can get it to produce decent results.