How can my AI agent pay for tools by itself?

Last updated: 2026-09-26

An AI agent can pay for Zambo tools by itself over x402: it receives an HTTP 402, pays $1.49 USDC on Base once, and gets a 24-hour Day Pass, not per call, with no account.

  1. Call https://zambo.dev/api/mcp free (20 calls per tool per day).
  2. POST https://zambo.dev/api/x402/day-pass (or call the MCP tool day_pass_activate) and receive the 402 challenge.
  3. Sign the EIP-3009 USDC authorization and retry the POST with X-Payment.
  4. Send X-Zambo-Key: <access_key> for 24 hours.

Our own test purchase: receipt 768e9f76. Learn about the x402 Day Pass. People: Zambo Pass $49/mo (pricing).

Frequently asked questions

How can my AI agent pay for tools by itself?

An AI agent can pay for Zambo tools by itself over x402: it receives an HTTP 402, pays $1.49 USDC on Base once, and gets a 24-hour Day Pass, not per call, with no account.

What does the agent send after paying?

The header X-Zambo-Key: <access_key> on requests to https://zambo.dev/api/mcp until expires_at.

Does the agent need an account or API key?

No. The free tier is 20 calls per tool per day with no key. The Day Pass is bought by the agent's own wallet over x402.