An Anthropic engineer’s cost guide says changing effort for Opus 5.5 preserves the cache with a subscription or direct API key, but requires rewriting it on Bedrock, Google Cloud and gateways. In a separate internal experiment with 370 Fable 5.1 attempts, passes rose from 140 at low effort to 214 at max, alongside higher token consumption. Failure classifications were approximations from a model judge. The proposed approach uses lower effort for implementation and higher effort for important verification while measuring cost per successful task in one’s own workload.