Claude Fable 5 is live on NeuralSpace: the first Mythos-class model
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Anthropic just shipped Claude Fable 5 — and this isn't another "3% better on benchmarks" release. For the first time in a while they've added a whole new class of models: Mythos. It sits above Opus, which until now was considered the ceiling. We plugged Fable 5 into NeuralSpace the same day we reached its API — here's what this thing is and what it costs.
So what is Mythos?
The Claude line-up used to read simply: Haiku — fast and cheap, Sonnet — the golden middle, Opus — the smartest. Now there's a fourth floor on top. Anthropic split it into two models: Fable 5 is available to everyone through the API, while Mythos 5 goes only to select organisations under a separate agreement. Under the hood, by Anthropic's own account, it's the same model — the difference is extra restrictions.
The practical part: the context window is one million tokens. That's roughly ten volumes of War and Peace in a single request. A whole mid-sized project, backend and frontend, fits in one window, and the model doesn't "forget" the start of the conversation an hour in.
What it costs — and the catch
The catch is the price, I'll be honest. Anthropic's official rate is $10 per million input tokens and $50 per million output. Twice the price of Opus 4.8. Inside NeuralSpace, thanks to partner access, it works out cheaper than the direct API: 760 tokens per million in, 3800 per million out.
Sounds abstract? Here's the concrete version: an ordinary question-and-answer in chat cost me 0.54 tokens. A long review of a couple thousand lines of code — somewhere around 10–20 tokens. The daily bonus tokens are enough to poke at the model without topping up at all.
How to try it in chat
Open the Chat section, and in the model dropdown pick Claude Fable 5 — it's right at the bottom, after Opus 4.8. That's it. Sign up with an email, no VPN needed, and no foreign card either.
Web search works — it's the checkbox under the model picker. You can attach images and documents too: PDF, TXT, DOC.
Fable in the code section
This is where it gets interesting. In the Code section Fable 5 is available as an agent model: you describe the project in words, and it writes the files, installs dependencies, and deploys the site to hosting itself. For complex projects we used to recommend Opus — now there's a more powerful option.
The million-token context really comes into its own here: the agent keeps the entire project in its head, not in fragments. Fewer of those "the model rewrote one function and broke three neighbours" moments.
Who actually needs it
Not everyone, and that's fine.
- Simple questions, translations, social posts — go with GPT-5 Mini or Sonnet, it'll be many times cheaper.
- Mid-level coding — Opus 4.8 is still a great choice, and it's half the price.
- But if you've got a big project, long documents, a complex architecture, or a task where other models start going in circles — Fable 5 is noticeably more confident. I fed it a tangled bug that Opus answered with "restart and see what happens" — Fable found the cause on its second message.
Documentation
For those who want to dig deeper: the official announcement is on Anthropic's site, and the API and pricing details live in the Claude docs. The model id is claude-fable-5, and the request format is the same as the other Claude models (the Messages API), so existing code moves over by changing a single line.
And if you'd rather skip the code — the model is already waiting in NeuralSpace chat. Daily bonus tokens are credited every day, enough to get acquainted.
Часто задаваемые вопросы (FAQ)
Вопрос: Как получить лучший результат от нейросети?
Ответ: Используйте подробные промпты (описания) на английском языке, задавайте стиль и детали сцены.
Вопрос: Можно ли использовать эти материалы в коммерческих целях?
Ответ: Да, сгенерированный контент полностью принадлежит вам.