My AI agent hit its daily free limit in the middle of a job

The job was moving, then a call came back refused and everything stopped. Nothing crashed and nothing was lost: the agent reached the end of its free day. This page says exactly where that line sits, what the refusal itself does, and the three ways forward, priced in plain numbers.

What the limit is, and why the job stopped

On Zambo, the free tier is 20 calls plus 1 wrap-up free every day, across 153 tools behind one MCP endpoint at https://zambo.dev/mcp. No account and no key are needed to use it. A multi-step job spends those calls one tool at a time: a price check here, a page fetch there, a file written, a lead scored. When call 21 arrives, the endpoint refuses it. The job did not fail. It ran out of free day, the same way a meter runs out, and it stops at the exact step where the limit landed.

The refusal is receipted, and it burns no quota

The refused call executes nothing and charges nothing, and it burns no quota. What it does issue is a verifiable AER-1 receipt with its own public run link, so the stop itself is recorded: which job, which call was refused, and when. Open a real receipt and check the shape of that record yourself: https://zambo.dev/run/e340c33c-ccec-458f-aa9d-fe98f4243969. A receipt proves the saved record was not changed after it was saved. It does not prove an answer was right, and this page does not claim otherwise. More than 108,000 public receipts have been issued through this endpoint, and the format behind them, AER-1, is closed at draft revision -26 with a public corpus of 143 vectors and 146 checks that anyone can run.

Way one: wait for tomorrow's free tier

The free tier resets daily: another 20 calls plus 1 wrap-up, free, no payment and no signup. If the job has no deadline, waiting costs nothing and the job record waits with it, because the calls already made are saved as receipts, not held in a chat that can vanish. Pick the job up tomorrow and continue from the record instead of reconstructing where it stopped.

Way two: Day Pass, $0.99, unlimited for 24 hours

If the job has to finish today, the Day Pass is the fix built for this exact moment: $0.99, one payment, unlimited calls for 24 hours, including unlimited wrap-ups, on the same endpoint and the same job. There is no subscription and no auto-renew. When the 24 hours end, access falls back to the free tier. The job resumes from its record, so the calls you already spent today are not spent again. More than 186,000 Zambo packages have been downloaded by people and agents setting this endpoint up, and the Day Pass is the step most of them take the first time a real job outgrows the free day.

Way three: the Pass, $29 per 30 days, for daily drivers

If your agent hits the free limit most days, stop buying days one at a time. The Zambo Pass is $29 per 30 days, one payment, on the same endpoint. The math is direct: $29 divided by $0.99 is about 29 days. Fewer heavy days than that in a month, day passes are cheaper. Work waiting on the agent every morning, the Pass is cheaper, and the daily limit stops being part of your planning.

How an agent pays, and how a human pays

An agent pays programmatically with USDC on Base through the x402 flow. It requests the challenge at GET /api/x402/day-pass, which returns an HTTP 402 carrying the payment terms: $0.99 in USDC on Base. It settles with POST /api/x402/day-pass, access opens for 24 hours, and the payment itself returns a verifiable receipt. No card form, no checkout page, no human in the loop. A human pays at zambo.dev/day-pass with a card or PayPal, and gets a private access key: paste it where the AI app asks for a key, or attach it as the X-Zambo-Key header on the endpoint. Either path buys the same 24 hours.

The fourth move, when another AI is closer: hand the job over

A limit in one place is not a limit everywhere. The free tier's 1 daily wrap-up still works after the calls run out, and picking up a handed-over job in another AI is always free. Wrap the stopped job, hand it over, and a second AI continues from the record: the goal, every finished step with its receipt, and what comes next. The work moves; the limit stays behind with the first AI's day.

Questions, answered

What happens when my AI agent hits its daily free limit in the middle of a job?

The next call is refused and the job stops where it stands. On Zambo the free tier is 20 calls plus 1 wrap-up every day across 153 tools at https://zambo.dev/mcp. The refusal executes nothing, and it still issues a verifiable AER-1 receipt with its own public run link, so the moment the job stopped is itself part of the record.

Does hitting the free limit burn quota or cost money?

No. A refused call burns no quota and charges nothing. The endpoint answers with a receipt for the refusal and runs no tool. Your remaining options are untouched: the wrap-up still works, and work already wrapped can still be picked up free in another AI.

How do I restart the same job today instead of waiting?

Buy the Day Pass: $0.99 for unlimited calls for 24 hours, including unlimited wrap-ups, on the same endpoint and the same job. The job resumes from its record instead of starting over, because every call before the limit already left a receipt in that record.

How does an agent pay for the Day Pass itself?

Programmatically, with USDC on Base through the x402 flow: the agent requests the challenge at GET /api/x402/day-pass, which returns an HTTP 402 with the payment terms ($0.99 in USDC on Base), then settles it with POST /api/x402/day-pass. Access opens for 24 hours and the payment itself returns a verifiable receipt. No checkout page and no human click are required.

How does a human pay for the Day Pass?

Open https://zambo.dev/day-pass/ and pay $0.99 by card or PayPal. You get a private access key; paste it where your AI app asks for a key, or attach it as the X-Zambo-Key header on the MCP endpoint. The same pass then works in every AI you use.

What if my agent hits the free limit every day?

Take the Zambo Pass: $29 per 30 days, one payment. Day passes win for bursty work, a research sprint or a demo day. The Pass wins when the agent works daily, because $29 divided by $0.99 is about 29 days of day passes.

Can I finish a limit-stopped job in another AI for free?

Yes, if the work was wrapped. The free tier includes 1 wrap-up every day, and picking up a handed-over job in another AI is always free. Wrap the job, hand it over, and the next AI continues from the record: goal, steps already done, and a receipt for each one.

Finish the job today

Zambo is the verifiable work layer for AI: 153 tools behind one MCP endpoint, continuity that carries work across AIs, and a verifiable AER-1 receipt for every job. Connect the endpoint at https://zambo.dev/mcp and the first 20 calls plus one wrap-up are free every day. Picking up a job in another AI is always free. When a job outgrows the free day mid-flight, a Day Pass is $0.99 for unlimited calls for 24 hours: zambo.dev/day-pass.