Levee / Learn / How to stop an AI agent overspending
How to stop an AI agent overspending
A step-by-step answer for teams giving agents a card.
Short answer: to stop an AI agent overspending, give it a hard budget and end date, limit where it can spend, route unusual purchases to a person, and enforce every rule at card authorization, outside the agent. Declined purchases should be recorded with a reason so you can review them.
Why agents overspend
Agents rarely overspend out of bad intent. They overspend because a loop repeats, a task is ambiguous, a price changes mid-purchase, or text on a page or in an email steers them somewhere unexpected. An agent also acts faster than anyone can watch, so a small error can be repeated many times before a person notices. The fix is not a better prompt. It is a limit the agent cannot talk its way past.
The seven steps
1. Define the job and its ceiling
Write down what the agent is for and the most it should spend on it. "Book travel for the conference, up to $3,000, until March 1" is a control you can check. "Handle travel" is not.
2. Set a total, a per-purchase limit and an end date
A total budget caps the task. A per-purchase limit catches a single bad charge. An end date means authority does not linger after the job is done.
3. Limit where it can spend
List the merchants or merchant categories the job needs and block the rest. Categories are broad, so use named merchants where you can. See why card limits and MCC blocks aren't enough on their own.
4. Use a separate card per job
Per-task or single-use cards keep one job's mistake from draining another's budget. They cap loss per card but not the rules behind it, which is why they work best alongside a spend mandate.
5. Add a human for the unusual
Decide in advance which purchases need a person: above a threshold, a new merchant, a change in currency. The agent asks, a human answers, and the answer is recorded.
6. Enforce outside the agent, and fail closed
The check has to run at card authorization, in a separate system the agent cannot change. If the system cannot decide in time, the payment is declined. This bounds the damage from a confused or manipulated agent: purchases outside what a human approved are declined. It does not stop every bad input, and it does not need to. Read more in AI agent spend controls.
7. Review and keep a kill switch
Look at approvals, declines and near misses each week. Keep a way to pause an agent's spending everywhere at once.
What not to rely on
- The prompt. "Never spend more than $500" is a hope, not a control.
- One shared company card. It mixes every agent's spend and gives you nothing to revoke cleanly.
- Statements after the fact. Reviewing charges next month tells you what happened, not what was stopped.
Putting it together as a mandate
These steps are easier to run as one unit. A spend mandate records the purpose, merchants, budget, limits and end date a human approved, and every authorization is checked against it. The guide to AI agent spend authorization walks through the flow, and the glossary defines the terms.
Where Levee fits
Levee is the authorization layer for AI agent spend. Levee lets a human approve what an agent may spend, enforces it at the moment of card authorization, outside the agent, and keeps tamper-evident proof of every decision. It is not a card issuer and never holds or moves money: cards stay with your issuing provider, such as Airwallex, and Levee works alongside the controls you already use.
Frequently asked questions
How do I stop an AI agent from overspending?
Give it a hard budget with an end date, limit it to the merchants it needs, send unusual purchases to a human, and enforce all of it at card authorization in a system the agent cannot change. Then review what it did.
Is a low credit limit enough to stop an AI agent overspending?
It bounds the worst case but not the cause. A low limit can still be spent entirely on the wrong merchant, and it is the same for every task. Pair it with merchant locks, per-task budgets and approvals.
Can I rely on the agent's own instructions to stay within budget?
No. Instructions are a request, and they can be overridden by a mistake, a bad tool result or text the agent reads. The limit has to be enforced where the agent cannot reach it.
What should happen when an agent hits its limit?
The payment should be declined, or paused for a person to approve, and the attempt recorded with the reason. A system that cannot decide in time should decline rather than approve.
What about runaway model or API costs?
Those are handled with usage budgets and alerts at the model provider or gateway. This guide covers purchases an agent makes with a card, where the money goes to a merchant.
Does Levee hold or move money?
No. Cards are issued by your issuing provider, such as Airwallex, and Levee makes the authorization decision and keeps tamper-evident proof of it. Levee never holds or moves money.
Related
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