Anthropic released Claude Fable 5 today — the first generally available model of the new Mythos class, positioned above the Opus line. And it's available in Zeptix right away: Business customers can switch their chatbots to claude-fable-5 in the model picker starting today.
What's new
- Claude Fable 5 — exclusive to the Business plan. Anthropic's strongest publicly available model: state of the art in software engineering, knowledge work, vision and long-running autonomous tasks — with a 1-million-token context window.
- Fair, transparent credits. A Fable 5 response costs 80 credits per message in language bots. Coding bots bill by length as usual (roughly 267 credits per request on average) — in line with GPT-5.5 (157) and Claude Opus 4.8 (133).
How to activate the model
- Open your dashboard and pick the bot you want to adjust.
- Go to the Models tab and select Claude Fable 5.
- Save — done. The next response runs on the new model.
On Starter and Pro plans the model is shown greyed out with a plan hint — upgrading to Business unlocks it instantly.
Good to know: safety and privacy
Fable 5 ships with new safeguards from Anthropic: requests in sensitive areas (cybersecurity, biology, chemistry) are automatically answered by the also very capable Claude Opus 4.8 — according to Anthropic this affects less than 5% of all sessions. In addition, Anthropic retains Fable 5 requests for a mandatory 30 days exclusively for safety purposes (no training, logged access). We've documented this transparently in our privacy policy and subprocessor list — and the model picker points it out directly.
For an in-depth take on what the Mythos class means and when Fable 5 is worth it for your bot, see the blog: Claude Fable 5 — the Mythos-class model at a glance.
Questions or feedback? Join the Discord community — that's also where you'll hear about new models first.