Claude Fable 5
Anthropic
Anthropic's first generally available Mythos-class model (June 2026) and its most capable widely released Claude, built for the most demanding reasoning and long-horizon agentic work. Runs with always-on adaptive thinking, a 1M-token context window, and 128K output, and shares Claude Mythos 5's weights with added safety classifiers that route flagged high-risk requests to Opus 4.8.
Strengths
- Anthropic's most capable generally available (Mythos-class) model
- Always-on adaptive thinking for demanding reasoning and long-horizon agentic work
- Leads nearly every published Anthropic coding and agentic benchmark
- Tops Anthropic's GDPval-AA economic-task leaderboard, above Opus 4.8
- 1M-token context window with text, image, and file inputs
- Built-in safety classifiers fall back to Opus 4.8 for flagged high-risk domains
Caveats
- Frontier pricing at $10/$50 - 2x Opus 4.8 and far above Sonnet 5
- Safety classifiers reroute flagged cybersecurity/biology/chemistry requests to Opus 4.8
- Briefly suspended in June 2026 under export-control directives before returning globally July 1
- Vendor
- Anthropic
- Context Window
- 1,000,000 tokens
- Max Output
- 128,000 tokens
- License
- Proprietary
- Release Date
- 2026-06-09
- Modalities
- textimage
Capabilities
Vision
Audio
Video
Tool Use
Resources
Pricing
$10 per 1M input tokens, $50 per 1M output tokens (2x Opus 4.8), reflecting frontier Mythos-class capability. Accepts text, image, and file inputs.