Cost Per Task

In one sentence

Cost per task is the fully attributed model (and related) spend required to attempt a defined unit of work.

Why it matters

Sticker price per million tokens hides retries, tool loops, and context growth. Task-level cost connects spend to engineering work.

How it works

• Define the task boundary (ticket, PR, agent session).
• Sum input, output, cached, and other billed token classes for that boundary.
• Apply the prices that applied when the usage occurred.
• Optionally add human review time as a separate cost line—do not silently mix units.
• Report assumptions: model, caching, what counted as “done.”

Example

Session used 800k input tokens ($X), 40k output tokens ($Y), 2M cached reads ($Z). Task cost ≈ X+Y+Z. If three retries repeated most of the work, say so—amortize or show retries as waste.