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Protocol

x402

Understand x402 payment and sign-in challenge handling.

x402 challenges return machine-readable payment requirements and are retried with payment proof headers.

Agent summary

  • Pay handles supported x402 payment challenges automatically after authorization.
  • x402 sign-in challenges are auth-only and should not be described as payment settlement.
  • Use the gateway URL returned by the provider catalog.
  • Do not attach arbitrary payment headers by hand.

Example

pay --sandbox curl http://localhost:3402/x402/joke

The bundled examples and debugger can show x402 challenge, facilitator, retry, and response phases when the endpoint supports them.

MPP

Understand Machine Payments Protocol charge and session challenges.

Wallet approval and security

Keep wallet authorization, provider content, and agent instructions separate.

On this page

Agent summaryExample