AI Research
Claude Opus 5.5: Anthropic's New Flagship Matches Fable 5.1 at 40% Less Cost — and Lands in GitHub Copilot
Anthropic launched Claude Opus 5.5 on September 22, 2026 — the first model in a new Claude 5.5 family and the company's most advanced model to date by its own account — and the headline claim is unusually double-edged for a flagship release. Opus 5.5 performs at the level of Claude Fable 5.1 for mo…