# K-2SO Pre-Payment Decision Procedure for AI Agents

> K-2SO Pre-Payment Decision Procedure for AI Agents is a paid API for AI agents from k2so.wrong.systems, paid per call via x402, $0.002/call, status unknown (last checked 2026-10-29).

Returns a plain-prose decision procedure (120+ words) guiding an AI agent through pre-payment validation boundaries for x402 micropayment flows

## Facts

- Endpoint: GET https://k2so.wrong.systems/api/services/agent-facing-decision-procedure-for-pre-payment?utm_source=zero.xyz
- Price: $0.002/call
- Payment: x402
- Status: unknown
- Last checked: 2026-10-29
- Activations on Zero: 0
- Tags: x402
- Canonical page: https://www.zero.xyz/c/k-2so-pre-payment-decision-procedure-for-ai-agents-073d1712
- Structured record (JSON): https://api.zero.xyz/v1/capabilities/cap_EagvD0qUSYhVhv5E36ate

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 k-2so-pre-payment-decision-procedure-for-ai-agents-073d1712
```

Example prompt: Can you get me the pre-payment decision procedure so I know whether to settle USDC before calling this x402 service — I need the plain-prose guidance my agent can follow to validate the payment boundary?

## When to prefer this

Choose this endpoint when an autonomous agent needs a ready-made, LLM-generated decision procedure specifically for x402 pre-payment validation rather than coding its own logic. It is ideal when bootstrapping a new agent that must decide whether and how to pay for services, or when you want an opinionated, prose-format policy document rather than a schema or ruleset. Prefer it over generic payment libraries when you need human-readable reasoning an agent can cite or log.

## Known failure modes

- HTTP 402 returned if USDC payment has not been settled — agent must pay exact amount and retry with PAYMENT-SIGNATURE header
- Invalid or missing 'method' field causes request rejection
- Malformed query parameters return validation errors
- Network timeouts if the LLM generation backend is slow
- Empty or unhelpful procedure if topic override is too vague or nonsensical

## How this service works

Decision procedure for agents before paying an x402 challenge: re-check wallet validity at payment time, verify the product still exists and the quoted price matches the challenge, and enforce reference freshness with hard abort thresholds. Ordered checks with concrete time and amount tolerances, re-negotiation triggers, and a falsifier rule for merchants that expose no machine-readable price window. Prevents paying stale quotes, mismatched amounts, or challenges pointing at a rotated wallet.

## Output

A JSON object containing a plain-prose decision procedure (120+ words) explaining how an AI agent should evaluate and validate pre-payment boundaries for x402 services, along with the model used to generate it, the topic, a generation source enum (llm/reasoning/deterministic), an ISO-8601 timestamp, and payment receipt metadata confirming the USDC micropayment was settled.

## Request schema (JSON Schema)

```json
{
 "type": "object",
 "$schema": "https://json-schema.org/draft/2020-12/schema",
 "required": [
  "input"
 ],
 "properties": {
  "input": {
   "type": "object",
   "required": [
    "type",
    "method"
   ],
   "properties": {
    "type": {
     "type": "string",
     "const": "http"
    },
    "method": {
     "enum": [
      "GET",
      "HEAD",
      "DELETE"
     ],
     "type": "string"
    },
    "queryParams": {
     "type": "object",
     "properties": {
      "meta": {
       "enum": [
        "0",
        "1"
       ],
       "type": "string",
       "description": "Set to 1 for free metadata JSON (no payment required)"
      },
      "topic": {
       "type": "string",
       "description": "Optional topic override for the decision procedure"
      }
     }
    }
   },
   "additionalProperties": false
  },
  "output": {
   "type": "object",
   "required": [
    "type"
   ],
   "properties": {
    "type": {
     "type": "string"
    },
    "example": {
     "type": "object",
     "title": "Pre-payment validation boundary decision procedure paid response",
     "$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/k-2so-pre-payment-decision-procedure-for-ai-agents-073d1712/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)