During early testing on our Browser Agent Evals, Opus 5.5 completely crushed it's predecessor Opus 5, but also Fable 5.1 & 5 in accuracy, speed, and, cost.
Compared to Opus 5 in the Claude Code harness it's roughly 5x cheaper per task, and 2x faster.
Introducing Claude Opus 5.5, the first model in our new Claude 5.5 family.
It performs at the level of Claude Fable 5.1 for most tasks, and costs 40% less to run than Opus 5.