Choosing the right Claude tier for each role in an agent workflow - orchestrator, default, parallel worker - by the job and token bill, not the benchmark.
Fable 5.1 for the hardest reasoning, Opus 5.5 to orchestrate at $4/$20, Sonnet 5.5 as the default worker, Haiku 4.5 for parallel grunt work. Pick by job.
Sonnet 5 is the default on Free and Pro at $2/$10 per million tokens - close to Opus 4.8 on Anthropic's launch benchmarks at 40% of the Opus input price.
Fable 5 is GA at $10/$50 per million tokens with a 1M context - and refusals arrive as HTTP 200, so integrations need refusal handling and a fallback.
Opus 5 keeps the $5/$25 price of Opus 4.8 with near-Fable agentic quality - within 0.5% of Fable on CursorBench at half the cost per task.
Opus 5.5 and Sonnet 5.5 break old request code: disabled thinking, forced tool_choice and the old computer-use tool now return a 400. Per-model checklist.