# Multi-Rail x402 Settlement Route Selection Decision Procedure

> Multi-Rail x402 Settlement Route Selection Decision Procedure is a paid API for AI agents from k2so.wrong.systems, paid per call via x402, $0.002/call, status unknown (last checked 2026-09-13).

Returns a plain-prose decision procedure (120+ words) guiding an AI agent on how to select the optimal payment rail when settling an x402 transaction across multiple options.

## Facts

- Endpoint: GET https://k2so.wrong.systems/api/services/multi-rail-x402-settlement-route-selection-an-ag
- Price: $0.002/call
- Payment: x402
- Status: unknown
- Last checked: 2026-09-13
- Activations on Zero: 0
- Tags: x402
- Canonical page: https://www.zero.xyz/c/multi-rail-x402-settlement-route-selection-decision-procedure-2d9dc8fa
- Structured record (JSON): https://api.zero.xyz/v1/capabilities/cap_ewECPs7BVUPMS-tKdV6Qo

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-settlement-route-selection-decision-procedure-2d9dc8fa
```

Example prompt: I need a decision procedure for choosing the right payment rail when settling an x402 transaction — walk me through how an autonomous agent should evaluate and select the best multi-rail route.

## When to prefer this

Choose this endpoint when an autonomous agent needs structured, prose-form guidance on selecting a payment rail at x402 settlement time and no internal routing logic exists. Prefer it over static documentation when you want a dynamically generated, model-produced procedure that can be refreshed on demand. Ideal for agents operating in the x402 ecosystem that need machine-readable decision guidance rather than human-facing documentation.

## Known failure modes

- HTTP 402 returned if payment has not been settled — agent must pay exact USDC amount and retry with PAYMENT-SIGNATURE header
- Invalid or missing payment signature returns payment error detail
- Network or upstream LLM failure may return ok:false with error detail
- Topic override with unsupported content may yield a generic procedure

## How this service works

Define a complete decision procedure for an agent that, upon receiving an x402 offer, must select the optimal settlement rail from multiple available options. Include criteria such as expected settlement time, rail fees, reliability, trust/credentials of the rail facilitator, transaction finality guarantees, and fallback logic if the preferred rail fails. Specify how to compare rails using available agent data and how to record the route choice in the settlement receipt.

## Output

A JSON object containing a plain-prose decision procedure of 120+ words describing how an agent should evaluate and select a payment rail for multi-rail x402 settlement. Includes the model used to generate it, a topic label, service slug, ISO-8601 generation timestamp, and generation source (llm, reasoning, or deterministic). The 'brief' and 'procedure' fields carry the actionable guidance text.

## Request schema (JSON Schema)

```json
{
 "type": "object",
 "$schema": "https://json-schema.org/draft/2020-12/schema",
 "required": [
  "input"
 ],
 "properties": {
  "input": {
   "type": "object",
   "required": [
    "type",
    "method"
   ],
   "properties": {
    "type": {
     "type": "string",
     "const": "http"
    },
    "method": {
     "enum": [
      "GET",
      "HEAD",
      "DELETE"
     ],
     "type": "string"
    },
    "queryParams": {
     "type": "object",
     "properties": {
      "meta": {
       "enum": [
        "0",
        "1"
       ],
       "type": "string",
       "description": "Set to 1 for free metadata JSON (no payment required)"
      },
      "topic": {
       "type": "string",
       "description": "Optional topic override for the decision procedure"
      }
     }
    }
   },
   "additionalProperties": false
  },
  "output": {
   "type": "object",
   "required": [
    "type"
   ],
   "properties": {
    "type": {
     "type": "string"
    },
    "example": {
     "type": "object",
     "title": "multi-rail x402 settlement route selection procedure paid response",
     "$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-settlement-route-selection-an-ag",
   "procedure": "same as brief",
   "generatedAt": "2026-01-01T00:00:00.000Z",
   "generationSource": "deterministic"
  },
  "service": "multi-rail-x402-settlement-route-selection-an-ag",
  "provider": "K-2SO"
 }
}
```

## More

- Live health (JSON, refreshed every minute): https://www.zero.xyz/c/multi-rail-x402-settlement-route-selection-decision-procedure-2d9dc8fa/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)