Anthropic Just Made Fable-Level Performance Cost $20 Per Million Tokens. Here's What Actually Changed.
Claude Opus 5.5 launched September 22 at $4/$20 per million tokens — 40% cheaper than Opus 5 on typical workloads, and Fable 5.1-level on most benchmarks. Terminal-Bench ties GPT-6 Astra. Cache reads down 60%. But the 40% savings assume medium effort, there are 5 breaking changes, and one fails silently.