x402 is an open protocol that uses the HTTP 402 "Payment Required" status code to let AI agents pay for API calls and services with stablecoins in real time. No cards, no invoices: the agent sends payment and the service responds. Syenite declares x402 support in its ERC-8004 agent registration so clients and other agents can discover that the MCP server is payment-ready.
Services that support x402 return 402 when a request requires payment. The response includes how much to pay and where. The client (or agent) sends the payment, then retries the request with proof. Settlement is on-chain and fast. The protocol is chain-agnostic; major implementations exist on Base, Solana, and others. It is designed for agent-to-agent and agent-to-service micropayments.
Syenite's agent registration document (/.well-known/agent-registration.json) includes "x402Support": true. That tells discovery clients and wallets that this agent can participate in x402 flows. The MCP endpoint itself today is free and rate-limited; x402 support is a declaration for future payment integration and for appearing in agent directories that filter by payment capability.
Fetch the registration document:
curl -s https://syenite.ai/.well-known/agent-registration.jsonCheck the x402Support field. The same document lists the MCP and web endpoints and, when configured, your on-chain agent ID (ERC-8004). Agents that support both ERC-8004 and x402 are discoverable as payment-capable DeFi tools.
DeFi operations (quotes, execution, data) can be monetized per call. x402 gives a standard way for an agent to pay for premium or high-volume use without API keys or billing dashboards. Syenite's position: one DeFi interface for AI agents, with registration and x402 support so the server can be found and paid when that model is adopted.
ERC-8004 agent registration with Syenite (how to register and what goes in the document). Why agentic DeFi. Tool list on the homepage.