Agent Budgets
Willow shows what each background agent costs and lets you cap it. A budget protects against an agent that runs far more, or far longer, than expected, for example a busy Slack channel or a task that keeps the agent working for hours.
Spend and budgets work for agents on Willow Agents and Claude Managed Agents. The cost is Anthropic's list price for the agent's sessions, as Anthropic reports it, whoever triggered them. Sessions started outside Willow, for example straight from the Anthropic API, are not counted.
See what an agent costs
| Where | Shows |
|---|---|
| The Cost column in the agents table | This week's spend, and the all-time total under it. |
| Cost wk on each card in the grid view | This week's spend. |
| The agent's Settings tab, Budget section | Spend today, this week, this month, and all time, and progress against the budget if one is set. |
Periods follow the UTC calendar: a day starts at 00:00 UTC, a week on Monday, and a month on the 1st.
Spend is refreshed when the agent is triggered, when you open its Budget section, and once an hour, so it can be up to an hour behind the agent's latest runs. Agents on other platforms show —.
Set a budget
- Open the agent and select the Settings tab.
- Open the Budget section.
- Turn on Spending cap, enter an amount in US dollars, and pick Daily, Weekly, or Monthly.
- Select Save.
To remove the budget, turn off Spending cap and select Save.
When the budget is reached
Willow checks the budget before every message the agent receives: Slack messages and workflow steps, API and webhook triggers, scheduled triggers, the invoke API, the Test Agent panel, and follow-ups you send from the Sessions tab. Once the period's spend reaches the budget, new messages are turned away until the period resets:
| What was blocked | What happens |
|---|---|
| A Slack message | The agent's bot replies in the thread with the reason, when the budget resets, and who can raise it. |
| An API, webhook, or invoke call | The call fails with status 429 and the same message. |
| A test or a follow-up from the agent page | The page shows the same message. |
| A scheduled trigger | The run is skipped. |
The message reads like this:
This agent has used its $50.00 weekly budget. It can run again when the budget resets (Mon, Oct 12, 00:00 UTC), or ask the agent's owner (Dana Levi) or a Willow admin to raise it.
The check runs before a message is delivered, so a run that is already going finishes even if it crosses the budget. Expect the final spend to land somewhat above the budget. A blocked message is not queued. Send it again once the budget resets.
Get past a budget
| Way | Who can do it |
|---|---|
| Wait until the period resets. The message says when. | Anyone. |
| Raise or remove the budget. A higher budget applies right away to the current period. | The agent's owners, and admins who can edit background agents. |