Explainer
What is paid MCP?
Charging for a tool call. Today that charge is an overlay — often x402 or a vendor gateway — not a core MCP message type.
Paid MCP means an agent discovers a tool, learns the price and payment method, pays, and then receives the tool result. The MCP spec still describes the tool; the payment protocol describes the 402.
Cloudflare’s Monetization Gateway explicitly lists MCP tools as chargeable resources via x402. Foundry’s own MCP transport is a challenge-handoff: it tells the caller how to pay. It does not sign as a buyer wallet.
Until MCP itself names a payment profile, vendors will keep inventing overlays. That is a standards risk and a product opportunity.