> ## Documentation Index
> Fetch the complete documentation index at: https://docs.darwin.so/llms.txt
> Use this file to discover all available pages before exploring further.

# Agent Usage

> Goal-level execution, runners, tools, and skills priced in dollars.

Agent usage covers billable work Darwin performs for a goal: agent execution rounds, runner time, paid tools, and skills. It appears as one expandable quote line with public dollar subcharges.

Clarification, scoping questions, quote review, approvals, status checks, and ordinary human input are free.

Darwin snapshots the applicable public usage catalog into the approved quote. A later catalog change cannot alter an existing authorization.

Usage is captured when billable work runs, even if no seller deal ultimately settles. Darwin reverses usage for Darwin-caused failures or another explicit billing correction.

Agent usage is not included in the Network-fee base. If expected usage would exceed the approved ceiling, execution pauses with `overage_approval_required`.