WHY WE PICKED IT
It is the current number one on the independent Artificial Analysis Intelligence Index, and it got there while costing less per task than the model it displaced: $2.03 average per index task against Fable 5's $2.75. The effort dial is the reason to pick it over a fixed-tier model, because one integration covers cheap high-volume calls and expensive long-horizon agent runs.
GETTING STARTED
Use it free in the Claude apps, or via the API at model id claude-opus-5. Start at medium effort and only move up if the task actually fails, because max effort can spend roughly 8x the output tokens of low for work that did not need it. If you send the same system prompt or codebase repeatedly, turn on prompt caching first: cache hits cost $0.50 per million against $5 uncached.
QUICK TIPS
1
Set effort per call rather than globally, cheap calls do not need max
2
Cache long system prompts and repeated context before optimising anything else
3
Benchmark cost per completed task, not cost per token, when comparing to Fable 5
4
Reach for max effort on terminal and multi-file refactor work, where the gap is largest
5
Measure on your own tasks, index rankings move within a few points
PRICING
Freemium
Free tier available
Free tier includes limited features. Paid plans unlock full access, higher usage limits, and commercial usage rights.
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