Claude Code's hidden effort_cost_index table reveals max tier costs vary wildly by model

Wsz2020 · reddit · 2026-09-18

A hidden effortcostindex table in the Claude Code binary shows per-model token cost per effort level (high=1). Sonnet 5's max tier costs +132% over xhigh, while Opus 5 flattens to just +6% — "max" means very different things per model. The UI string confirms costs are per attempt, not per success, with no retry pricing. The author's own 8-agent measurement (2 tasks x 4 levels on Opus 5) confirmed the direction and nailed the key prediction: xhigh and max output tokens were nearly identical (397,827 vs 397,761). No documentation exists on how the catalog numbers were derived — treat as vendor estimates.

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