Use the x402 skill to decode the HTTP 402 response body I provide. Explain the amount, token, recipient, and expiry before any payment.
Required inputs
An HTTP 402 response body to inspect.
Access to the documented chaingpt_x402_decode tool.
Previously published starter task based on a pinned source version; check the source and required inputs before running. Task evidence ↗
SKILL.md
name: x402description: x402 agentic payments (Coinbase's HTTP 402 protocol). Custody-free tools to pay x402-protected endpoints (build the EIP-3009 transferWithAuthorization the payer signs, assemble the X-PAYMENT header), call a facilitator (verify/settle/supported), and monetize your own API by generating PaymentRequirements. USDC on Base. Triggers: x402, HTTP 402, pay per request, agentic payment, machine payment, X-PAYMENT, transferWithAuthorization, EIP-3009, facilitator, monetize API, pay for API, agent pays.
x402 Payments skill
x402 turns HTTP 402 Payment Required into a real payment rail for agents: a
server replies 402 with what it wants paid; the client signs an off-chain
authorization and retries with an X-PAYMENT header; a facilitator broadcasts
it. Settlement uses EIP-3009 transferWithAuthorization (e.g. USDC on Base) —
the facilitator can only broadcast the signed authorization, never alter the
amount or destination.
Custody-free: the plugin builds the EIP-712 the payer signs and assembles
the header; it never holds a key.
Tools
Tool
Purpose
chaingpt_x402_decode
Decode a 402 body or X-PAYMENT header into human terms (amount/token/recipient/expiry) before paying.
chaingpt_x402_build_payment
Build the UNSIGNED EIP-3009 typed data; pass a signature back to get the final X-PAYMENT header.
chaingpt_x402_facilitator
Call a facilitator: supported / verify / settle.
chaingpt_x402_create_requirements
Server side: generate the PaymentRequirements + 402 body to monetize your endpoint.
chaingpt_x402_fetch
The whole client loop in one tool: fetch a URL; on 402 it decodes the challenge and (given from) emits the unsigned typed data; re-call with xPaymentHeader to complete the paid request.
Pay an endpoint (client flow)
Fast path — one tool drives the loop:
chaingpt_x402_fetch url=<resource> from=<payer> → on 402 you get the decoded price/payee AND the unsigned EIP-3009 typed data.
Sign the typed data in the payer's wallet.
chaingpt_x402_build_payment from=<payer> requirements=<from step 1> signature=0x… → the X-PAYMENT header.
chaingpt_x402_fetch url=<resource> xPaymentHeader=<header> → the paid response.
chaingpt_x402_create_requirements network=base amount=0.01 payTo=<you> → serve
the returned JSON with HTTP 402. Verify/settle incoming payments via a
facilitator (chaingpt_x402_facilitator).
Known EIP-3009 tokens: USDC on base and base-sepolia. For other tokens pass
full PaymentRequirements (with asset + extra.name/extra.version).
0 ChainGPT credits.