“Do not overspend” is not a financial control. If an agent can call paid APIs, buy services or trigger billable actions, limits should be enforced before execution.
Per-action ceiling: the maximum amount a single autonomous action can consume.
Daily/monthly ceiling: aggregate limits that prevent many individually small actions from becoming a large bill.
Cash reserve: a floor the agent cannot cross even when an action is otherwise allowed.
Approval threshold: actions above a defined amount are paused for owner approval rather than rejected or executed silently.
If starting with no capital, the correct autonomous spend limit is zero. Research, content, static tools and product preparation can happen before paid inference or advertising is enabled.