# Multi-Rail x402 Payment Feasibility Routing Procedure

> Multi-Rail x402 Payment Feasibility Routing Procedure is a paid API for AI agents from k2so.wrong.systems, paid per call via x402, $0.002/call, status unknown (last checked 2026-09-14).

Evaluates and ranks candidate payment rails (Base x402, XRPL, Algorand, banking) for a given USDC payment amount and payer policy, returning per-rail feasibility verdicts, costs, and a ranked recommendation.

## Facts

- Endpoint: GET https://k2so.wrong.systems/api/services/multi-rail-x402-payment-feasibility-routing-give
- Price: $0.002/call
- Payment: x402
- Status: unknown
- Last checked: 2026-09-14
- Activations on Zero: 0
- Tags: x402
- Canonical page: https://www.zero.xyz/c/multi-rail-x402-payment-feasibility-routing-procedure-7125cbef
- Structured record (JSON): https://api.zero.xyz/v1/capabilities/cap_qbMYY4xlPOWJSADNozrPd

Status and success rate cover calls made through Zero and Zero's own probes. Third-party monitors may report differently.

## How to call it through Zero

Zero handles the 402 payment challenge and records the run. With the Zero CLI installed (`npm i -g @zeroxyz/cli`):

```sh
zero fetch --capability multi-rail-x402-payment-feasibility-routing-procedure-7125cbef
```

Example prompt: I need to send 0.15 USDC to a payee — check which of Base x402, XRPL, and Algorand rails are feasible given my per-call cap of 0.20 USDC and a daily budget of 5 USDC, and tell me which one you'd recommend based on lowest total cost and fastest settlement.

## When to prefer this

Use this endpoint when an autonomous agent or operator needs to programmatically select the optimal payment rail for a USDC transaction while enforcing spending policy constraints (caps, budgets, allowlists). Prefer it over manual rail selection when multiple rails (Base x402, XRPL, Algorand, banking) are available and fee/latency tradeoffs matter, or when policy compliance must be verified before committing a payment.

## Known failure modes

- Payment amount exceeds per-call cap — rail returns blocked-by-cap verdict
- Payee not on allowlist — rail returns not-allow-listed verdict
- Rail unavailable or unreachable — rail returns rail-unavailable verdict
- Daily budget exhausted — all rails may return blocked-by-cap
- Missing or malformed input parameters — returns error or incomplete feasibility matrix
- Payment insufficient to cover service fee ($0.002 USDC) — 402 response before result is returned

## How this service works

Machine-readable decision procedure for multi-rail x402 payment routing. Inputs: payment amount in USDC, payer spending policy (per-call cap, daily budget, allow-listed payees), candidate rails with their fee schedules and settlement latencies (Base x402, XRPL facilitator, Algorand, regulated banking rails). Outputs: per-rail feasibility verdict (settles, blocked-by-cap, not-allow-listed, rail-unavailable), total cost per rail including fee, settlement speed class, a ranked recommendation, and

## Output

Returns a structured decision object with: per-rail feasibility verdicts (settles, blocked-by-cap, not-allow-listed, rail-unavailable), total cost per rail including fees, settlement speed class for each rail, a ranked recommendation, and a human-readable decision procedure prose brief for agents.

## Request schema (JSON Schema)

```json
{
 "type": "object",
 "$schema": "https://json-schema.org/draft/2020-12/schema",
 "required": [
  "input"
 ],
 "properties": {
  "input": {
   "type": "object",
   "required": [
    "type",
    "method"
   ],
   "properties": {
    "type": {
     "type": "string",
     "const": "http"
    },
    "method": {
     "enum": [
      "GET",
      "HEAD",
      "DELETE"
     ],
     "type": "string"
    },
    "queryParams": {
     "type": "object",
     "properties": {
      "meta": {
       "enum": [
        "0",
        "1"
       ],
       "type": "string",
       "description": "Set to 1 for free metadata JSON (no payment required)"
      },
      "topic": {
       "type": "string",
       "description": "Optional topic override for the decision procedure"
      }
     }
    }
   },
   "additionalProperties": false
  },
  "output": {
   "type": "object",
   "required": [
    "type"
   ],
   "properties": {
    "type": {
     "type": "string"
    },
    "example": {
     "type": "object",
     "title": "Multi-rail x402 payment feasibility routing procedure paid response",
     "$schema": "https://json-schema.org/draft/2020-12/schema",
     "required": [
      "ok",
      "paid",
      "service",
      "provider",
      "result"
     ],
     "properties": {
      "ok": {
       "type": "boolean"
      },
      "paid": {
       "type": "boolean"
      },
      "result": {
       "type": "object",
       "required": [
        "ok",
        "service"
       ],
       "properties": {
        "ok": {
         "type": "boolean",
         "description": "Handler success"
        },
        "brief": {
         "type": "string",
         "description": "Decision procedure prose for agents"
        },
        "model": {
         "type": "string"
        },
        "topic": {
         "type": "string"
        },
        "service": {
         "type": "string",
         "description": "Service slug"
        },
        "procedure": {
         "type": "string"
        },
        "generatedAt": {
         "type": "string",
         "description": "ISO-8601 timestamp"
        },
        "generationSource": {
         "enum": [
          "llm",
          "reasoning",
          "deterministic"
         ],
         "type": "string"
        }
       }
      },
      "payment": {
       "type": "object",
       "properties": {
        "code": {
         "type": "string"
        },
        "payer": {
         "type": "string"
        },
        "detail": {
         "type": "string"

… (truncated)
```

## Response schema (JSON Schema)

```json
{
 "type": "json",
 "example": {
  "ok": true,
  "paid": true,
  "result": {
   "ok": true,
   "brief": "plain prose decision procedure (120+ words)",
   "model": "deepseek/deepseek-v4-flash-0731",
   "topic": "string topic",
   "service": "multi-rail-x402-payment-feasibility-routing-give",
   "procedure": "same as brief",
   "generatedAt": "2026-01-01T00:00:00.000Z",
   "generationSource": "deterministic"
  },
  "service": "multi-rail-x402-payment-feasibility-routing-give",
  "provider": "K-2SO"
 }
}
```

## More

- Live health (JSON, refreshed every minute): https://www.zero.xyz/c/multi-rail-x402-payment-feasibility-routing-procedure-7125cbef/health.json
- [Zero catalog index](https://www.zero.xyz/llms.txt)
- [Other services from k2so.wrong.systems](https://www.zero.xyz/host/k2so.wrong.systems/llms.txt)