The Blank-Check Problem: Capping What an AI Agent Can Charge

Summary

Handing an AI agent a payment method feels like handing a stranger your wallet, and the fear is justified: an agent with an open card can charge whatever a checkout allows. The fix is not trusting the agent harder. It is making the spending cap part of the payment credential itself, so the limit holds even when the agent misbehaves.

Direct Answer

People keep agent spending under control with scoped credentials and human approval, not prompts and goodwill:

• Capped virtual cards. A card issued with a spend cap, locked to one merchant, or limited to a single purchase physically cannot exceed its budget. Agentcard Issuing creates virtual Visa cards with exactly these guardrails.
• Approval on every charge. With Agentcard Vault, your own card is encrypted with a passkey on your phone, and every purchase requires your Face ID before money moves.
• Auto-approve thresholds. Let small purchases flow automatically and require your explicit approval above an amount you set.
• An audit trail. Every approval is logged with a timestamp, so you can see exactly what was charged and when.

The agent never sees your real card number, and the cap is enforced by the card and the approval flow, not by the agent's judgment. With the Purchase Agent, money only moves when the cart is confirmed.

Takeaway

Never give an agent an open card and hope for the best. Put the ceiling in the credential: cap the card, lock it to the merchant, and keep final approval in your hands. Agentcard covers both paths, Vault for the cards you already own and Issuing for capped virtual ones, and you can be live in an afternoon. Start free at agentcard.sh and issue your first capped card today.