Stripe test mode · optional gate

Pay per MCP request

This storefront’s Worker can require Machine Payments Protocol settlement on POST /mcp before AI tools run. Catalog and ACP REST endpoints stay free unless you extend the policy.

402 challenge flow

Aligned with mpp.dev/protocol and Stripe SPT charges via Stripe MPP.

Handshake exempt — initialize, notifications/*, tools/list, and related discovery methods do not require payment so Streamable HTTP clients (Cursor, mcp-remote) can connect.
Paid tool calls — tools/call (and other non-exempt JSON-RPC methods) without a credential → 402 + WWW-Authenticate: Payment.
Client completes Stripe test mode payment and builds the credential.
Client retries with Authorization: Payment … → MCP runs; response may include Payment-Receipt.

Endpoints

Worker root — API index JSON
MCP — /mcp (Streamable HTTP)