Anthropic Launches Claude Fable 5 — A Mythos-Class Model for Everyone
The first model of the Claude 5 family lands in Claude's paid plans today — included until June 22, then available through usage credits at API rates.
By TSS Team
A Tier Above Opus
Anthropic today released Claude Fable 5, the first model in the new Claude 5 family and part of a "Mythos-class" tier that sits above Claude Opus. It shares its underlying model with Claude Mythos 5, which remains restricted to pre-approved organisations; Fable 5 is, in Anthropic's words, "a Mythos-class model that we've made safe for general use." In sensitive areas — offensive cybersecurity, biology, chemistry — safety classifiers automatically fall back to Claude Opus 4.8, though Anthropic says at least 95% of sessions run entirely on Fable's own responses. The specs are serious: a one-million-token context window and up to 128K output tokens per request.
What Subscribers Get
From today through June 22, Fable 5 is included at no extra cost on Pro, Max, Team, and seat-based Enterprise plans. On June 23 Anthropic will remove it from those plans, after which using it requires prepaid usage credits that draw down at the same per-token prices as the API — $10 per million input tokens and $50 per million output tokens, double Opus 4.8's rates but less than half the price of Claude Mythos Preview. Notably, Anthropic says that once capacity allows, it aims to restore Fable 5 as a standard part of subscription plans.
Early Reactions
The first reviews are striking. Stripe said Fable 5 "compressed months of engineering into days," reporting a roughly 50-million-line codebase migration done in a day. Cursor CEO Michael Truell said it has "opened up a class of long-horizon problems that were out of reach." Independent researcher Simon Willison called it "something of a beast — it's slow, expensive and has been quite happily churning through everything I've thrown at it so far."
Why It Matters to Us
TSS runs on Claude daily — a Claude Max subscription sits in our own expense ledger, powering our engineering, software and research work. A genuine step-change in long-horizon coding and reasoning doesn't just make headlines for a company like ours; it lands directly in the toolkit. We'll be making the most of the included window through June 22, and watching closely to see whether Fable 5 earns a permanent place in the plans.
Official sources & further reading
The frontier just moved again — and this time it shipped straight into the tools we use every day.