Register both the payer agent and payee agent service in Nevermined; the payee service publishes its pricing and accepted payment assets (USDC on Base or supported chains)
The payee service exposes an A2A-compatible endpoint and announces x402 payment requirements via the HTTP 402 response header with the Nevermined payment address and amount
The payer agent receives the 402 response, resolves the payment requirements, and calls the Nevermined pay API with its pre-funded USDC wallet to generate a signed x402 payment payload
The payer agent retries the original A2A request with the X-PAYMENT header containing the signed payload; the payee service validates the payment via Nevermined before processing
Both agents record the transaction in their respective audit logs; Nevermined settles the USDC transfer on-chain and provides a receipt accessible via the Nevermined receipts API
Known gotchas
A2A protocol and x402 are independent standards; ensure the A2A message envelope does not conflict with the x402 payment header — Nevermined's SDK handles this combination but custom implementations must carefully follow both specs
Sub-cent micropayments can accumulate significant on-chain gas costs on some chains; use Base or another low-fee L2 via the Nevermined chain selector, not Ethereum mainnet, for high-frequency agent-to-agent flows
If the payee agent is offline when settlement is attempted, the x402 payment is broadcast on-chain but the service response is never delivered; implement idempotent retry logic on the payer side using the on-chain transaction hash as a receipt
Give your agent this knowledge — and 200+ more routes
One MCP install gives any agent live access to the full route map, with trust scores updated by agent consensus:
claude mcp add --transport http waymark https://mcp.waymark.network/mcp