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
Tool discovery, payment authorization and evidence across agent calls
SML-X402-0044-PAGE PDF$29 ONE TIMEINSTANT DELIVERY
THE OUTCOME
Add payment to MCP tool use without hiding price, recipient or authorization from the controlling policy.
Primary search intent: MCP payments
CORE MODEL
Four ideas before action.
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
A six-step review process.
- 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
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
Before you 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.