Anthropic Launches Claude Fable 5, the First Public Mythos-Class Model
Anthropic announced Claude Fable 5 on June 9, 2026 - the first publicly available Mythos-class model, state-of-the-art on nearly all tested capability benchmarks.
Anthropic on Monday announced Claude Fable 5, the first Mythos-class model ever made available to the general public, alongside a restricted sibling called Claude Mythos 5. The company says Fable 5 is state-of-the-art on nearly all tested capability benchmarks, with its largest advantages on long and complex tasks.
A Mythos-Class Model, Made Safe for General Use
Claude Fable 5 shares the same underlying model as Claude Mythos 5, but has been made safe for general availability. Mythos 5, by contrast, has safeguards lifted in some areas and is restricted to cyberdefenders and infrastructure providers through Project Glasswing, with select biomedical researchers gaining access later through a trusted access program.
The headline numbers are striking. Fable 5 scores 80.3% on SWE-Bench Pro, roughly 11 points ahead of the next frontier model, with Claude Opus 4.8 at 69.2%, GPT-5.5 at 58.6%, and Gemini 3.1 Pro at 54.2%. It also posted the highest score among frontier models on Cognition's FrontierCode eval.
Beyond Coding
Anthropic highlighted capabilities well beyond software engineering:
- Vision: state-of-the-art at extracting numbers from scientific figures and rebuilding web apps from screenshots; the model completed Pokémon FireRed using only vision.
- Long context: support for millions of tokens; with file-based memory, Fable 5 played Slay the Spire 3x better than Opus 4.8.
- Early customer results: Stripe reported that a 50-million-line Ruby codebase migration was completed in one day, versus over two months for a team.
Availability and Pricing
Claude Fable 5 is included free on Pro, Max, Team, and Enterprise plans from June 9 through June 22, 2026; from June 23 it requires usage credits. It is fully available on the Claude API and generally available on Amazon Bedrock and GitHub Copilot as of June 9. API pricing is set at $10 per million input tokens and $50 per million output tokens - less than half the price of Claude Mythos Preview, and double Opus 4.8's $5/$25.
The Safety Story
TechCrunch noted the release came just days after Anthropic warned that AI is getting too dangerous. Anthropic says Fable 5 ships with cybersecurity classifiers that route triggered queries to Claude Opus 4.8 instead, triggering on less than 5% of sessions on average, and that more than 1,000 hours of external red-teaming found no universal jailbreaks.