# Multi-Rail x402 Settlement Route Selection Procedure

> Multi-Rail x402 Settlement Route Selection Procedure 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 an AI-generated decision procedure for selecting the optimal payment settlement rail when an agent receives an x402 offer with multiple rail options.

## Facts

- Endpoint: GET https://k2so-8080.on.ascii.dev/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-procedure-1bab93a7
- Structured record (JSON): https://api.zero.xyz/v1/capabilities/cap_fYIRqMQhDaP5K2VpPgkNm

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-procedure-1bab93a7
```

Example prompt: Walk me through the complete decision procedure for picking the best settlement rail when my agent gets an x402 offer with multiple options — covering how to weigh fees, settlement speed, finality guarantees, facilitator trust, and what to do if the top-ranked rail fails.

## When to prefer this

Use this endpoint when building an autonomous agent that must programmatically choose among multiple x402 settlement rails and needs a structured, vetted decision procedure rather than implementing ad-hoc logic. Prefer this over general finance or payment routing APIs when the context is specifically x402 protocol payments, multi-rail comparison, and agent-readable procedural guidance.

## Known failure modes

- Payment required but not provided — returns 402 with payment instructions
- Invalid query parameters — returns validation error
- LLM generation failure — ok field is false with error detail
- Rate limiting or upstream AI service unavailability
- Topic override parameter unrecognized or out of scope

## 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 structured prose decision procedure (the 'brief' or 'procedure' fields) generated by an LLM or reasoning system, covering: criteria for comparing rails (fees, settlement time, reliability, facilitator trust, finality), a scoring/ranking method using available agent data, fallback logic if the preferred rail fails, and guidance on recording the route choice in the settlement receipt. Response includes metadata like generatedAt timestamp, model used, and generation source.

## 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)
```

## More

- Live health (JSON, refreshed every minute): https://www.zero.xyz/c/multi-rail-x402-settlement-route-selection-procedure-1bab93a7/health.json
- [Zero catalog index](https://www.zero.xyz/llms.txt)
- [Other services from k2so-8080.on.ascii.dev](https://www.zero.xyz/host/k2so-8080.on.ascii.dev/llms.txt)