Guide
Let your agent pay for its own tools
Short answer: An AI agent can pay for tools on its own when the tool accepts a machine payment like x402, where the server answers "payment required" and the agent pays from its own wallet. On Zambo, the agent buys a $0.99, 24-hour Day Pass in USDC on Base, within the wallet policy you set, and keeps working.
The problem: paywalls stop agents
Autonomous agents run while you're away. When a tool hits a limit, a normal checkout needs a person to type a card number. The job stops until you come back.
x402 is built on the web's "402 Payment Required" response. The server tells the agent the price, the agent pays, and then it retries the request. There's no form and no human step, but only inside the rules you gave the agent's wallet.
How Zambo's limits work
Most Zambo tools are free up to 20 calls per tool per day, with a separate counter per tool that resets at UTC midnight. Some tools, like capability_search, credithunt and day_pass_status, are free with no cap. Past the cap, the tool replies with a 402, and that's when a Day Pass comes in.
Step by step: the agent pays its own way
- Connect. Point the agent at
https://zambo.dev/mcp. No key. - Keep one session. The agent uses the same
_session_idfor the whole job, so the pass and the receipts attach to that job. - Check headroom (optional).
zambo_limitshows how many free calls are left per tool and the current tier. - Hit the limit. At the cap, the tool returns 402 with the price: $0.99 for 24 hours.
- Pay. The agent calls
day_pass_activateand pays $0.99 in USDC on Base with x402, under its own wallet policy. - Confirm.
day_pass_status, which is always free, checks the pass using the same_session_id. - Retry and finish. The agent reruns the call and completes the job. Every call still returns a verifiable receipt.
- Close the job.
workflow_closegathers the job's receipts into one summary receipt you can review when you're back.
If a person is around: day_pass_checkout_link creates a 30-minute short link for a human-approved $0.99 Day Pass by card or PayPal, and day_pass_activate finishes the setup.
Keep it safe
- Give the agent a wallet with a small budget and clear limits. The wallet policy is your control.
- One Day Pass is $0.99 for 24 hours. There's no subscription to cancel.
- The purchase call returns a receipt too, so you can see exactly when the agent paid.
What you get
- A finished job instead of a stalled one.
- A verifiable receipt for every call, including the payment step.
- A summary receipt for the whole run.
- A handover link if the job was for a client (
handover).
A receipt shows the saved output hasn't changed since the call. It doesn't prove the output is correct.
Related
- Day Pass
- x402 agent payments guide
- Agent payments
- Fund your agent
- x402 Day Pass
- Let an AI agent pay with USDC
- Pricing
FAQ
Can an AI agent pay for a tool without me approving each purchase?
Yes, within the wallet policy you set. On Zambo, the agent buys a $0.99 Day Pass with x402 in USDC on Base.
What is x402?
A way for a server to answer "payment required" with a price, so a program can pay and retry without a checkout page.
What does the Day Pass cover?
24 hours of use past the free per-tool daily limits, tied to the agent's session.
How do I stop an agent from overspending?
Fund its wallet with a small amount and set limits in the wallet policy. Each Day Pass is a one-time $0.99.
Can a human buy the Day Pass instead?
Yes. day_pass_checkout_link gives a 30-minute link to pay by card or PayPal.
CTA: Paste zambo.dev/mcp into your AI. Your agent can buy its own Day Pass when it needs one.