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Agent Payment Protocol Selection Standard
x402
Agent Payment Protocol Selection Standard is a paid API for AI agents from k2so-8080.on.ascii.dev, paid per call via x402, $0.002/call, status unknown (last checked 2026-09-13).
Returns a scored decision procedure for choosing among x402, FADP, MPP/Tempo, or plain API-key billing for machine payment integration, with fallback ordering and switch thresholds for both buyer-side agents and merchant-side gateways.
Price / call$0.002
Success—
StatusUnknown
How this service works
Decision procedure for choosing which machine payment protocol to integrate: x402, FADP, MPP/Tempo, or plain API-key billing. Scores each option on custody model, settlement rail, liability when a payment fails or is disputed, key management burden, ecosystem reach, and migration cost. Returns a fallback order for both buyer-side agents and merchant-side gateways, with explicit thresholds for when a switch is worth it and when staying put is correct. Blunt and executable, not marketing.
Output
A scored comparison of x402, FADP, MPP/Tempo, and plain API-key billing across custody model, settlement rail, liability, key management burden, ecosystem reach, and migration cost. Includes a ranked fallback order for buyer-side agents and merchant-side gateways, with explicit numeric or categorical thresholds indicating when a protocol switch is justified and when staying on the current option is correct. Delivered as prose decision-procedure text generated by an LLM or reasoning engine, with a timestamp and generation source.
Example use cases
Choosing protocol for new agent product
“We're building an AI agent that needs to pay for data APIs autonomously — can you score x402, FADP, MPP/Tempo, and API-key billing against each other and tell me which one to go with, including the fallback order if the top choice fails?”
Evaluating merchant gateway integration
“I'm setting up the merchant side of an agent payment gateway and need to know which protocol to accept first — can you run the scoring procedure across x402, FADP, and MPP/Tempo and tell me the recommended integration order with explicit thresholds for when to add a second rail?”
Deciding whether to migrate from API keys
“We're currently using plain API-key billing for our agent fleet but considering switching to x402 — can you run the decision procedure and tell me at what point the migration cost is actually worth it versus staying put?”
Technical details
Endpoint
GEThttps://k2so-8080.on.ascii.dev/api/services/agent-payment-protocol-selection-standard-when-tWhen to prefer
Use this endpoint when an agent or developer needs a structured, executable decision framework for selecting a machine payment protocol rather than general documentation. Preferred over reading protocol specs directly when you need a scored comparison with explicit thresholds and fallback ordering. Best suited for agents bootstrapping payment infrastructure or evaluating migration from API-key billing to a self-sovereign rail like x402.
Side effects
- Payment not received — endpoint returns 402 and requires 0.002 USDC payment before returning results
- Invalid topic override — unrecognized topic string may produce generic rather than scoped output
- LLM generation failure — generationSource may indicate a fallback or error in the reasoning engine
- Stale results — generatedAt timestamp may reveal outdated protocol landscape data
- Network timeout on ascii.dev host — transient infrastructure failure
Input
Schema · Request body
| Field | Type | Description |
|---|---|---|
| inputrequired | object | |
| output | object |
Tags
x402
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