Paste an x402-payable endpoint URL, HTTP or MCP. Read-only diagnostics: no wallet, no payment, no risk. Try an example.
The code that fixes these problems, for your stack, filled in with your own payTo, amount, network and route.
You pay $0.05 in USDC on Base; your wallet shows a signature for exactly that amount to our payout wallet 0x6B0F…5F25. MetaMask's security check may call that wallet "untrusted" because it is a regular wallet rather than a contract; that is normal for x402 payments, and the signature can only move this one amount, once. Want a second opinion before you sign? presign-guard reads any signature request and tells you what it can move and to whom. Agents: GET /api/v1/fix?url=…