Claude Platform release notes — September 1, 2026
We've launched Claude Fable 5.1 ( claude-fable-5-1 ), the successor to Claude Fable 5 for long-running agentic coding, knowledge work, and research, alongside Claude Mythos 5.1 ( claude-mythos-5-1 ) f…
Added 2
- Launched Claude Fable 5.1 model for long-running agentic coding, knowledge work, and research
- Launched Claude Mythos 5.1 model