Discovery is not authorization
A tool description can advertise paid capability but should not grant spending permission.
Agent Commerce & Security · PDF FIELD GUIDE · 2026
MCP Payments Guide
The MCP Payments Guide (SML-X402-004) is a four-page PDF that shows how to add payment to MCP tool use without hiding price, recipient or authorization from the controlling policy. Its four core ideas are that discovery is not authorization, you quote the exact invocation, policy stays outside the seller, and tools return structured evidence, for a one-time $29 purchase.
Tool discovery, payment authorization and evidence across agent calls
SML-X402-0044-PAGE PDF$29 ONE TIMEINSTANT DELIVERY
THE OUTCOME
What is the goal of this guide?
The goal is to add payment to MCP tool use without hiding price, recipient or authorization from the controlling policy.
Use this guide to: Review MCP payment boundaries, tool-call approval and verification of paid delivery.
CORE MODEL
What four ideas come before action?
Before acting, work through four ideas: discovery is not authorization, quote the exact invocation, keep policy outside the seller, and return structured evidence.
Quote the exact invocation
Bind cost and scope to arguments, identity, expiry and expected output.
Keep policy outside the seller
The buyer or its delegated controller should enforce caps and allowed destinations.
Return structured evidence
Tool results should distinguish settlement, execution and accepted output.
ACTION CHECKLIST
What does the six-step review process cover?
The six-step review process covers declaring paid behavior in tool metadata, requesting a scoped quote, applying buyer-side spend policy, confirming recipient and network, correlating payment with tool call, and returning receipt and delivery state.
- Declare paid behavior in tool metadata
- Request a scoped quote
- Apply buyer-side spend policy
- Confirm recipient and network
- Correlate payment with tool call
- Return receipt and delivery state
PRIMARY SOURCES
How do I verify the moving parts?
The PDF includes a source map and explicit research boundary. Product and regulatory details can change; current official material controls.
x402 protocol documentation →x402 specification repository →Model Context Protocol specification →OWASP API Security Top 10 →TRUTH BOUNDARY
MCP implementations differ; verify the active specification and host security model.
AI tools assisted drafting and layout. SCRIPTMASTERLABS is responsible for editorial structure and source selection. No personalized investment, legal, tax, medical, regulatory, advertising or cybersecurity advice.
FAQ
What should I know before I buy?
What format is this product?
A four-page PDF field guide delivered immediately after successful Stripe Checkout.
Is this a subscription?
No. It is a one-time purchase.
Does this guarantee a result?
No. MCP implementations differ; verify the active specification and host security model.
Mcp server with x402: what is included?
4 pages in a fixed-layout PDF: Paid MCP tool calls, approval boundaries and delivery checks. This is a compact field guide with review checks and source notes.