# Paid Tool Request Scoping and Receipt Binding Standard

> Paid Tool Request Scoping and Receipt Binding 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 2026-10-10).

Returns a decision procedure for scoping any paid tool call into a minimal, bounded request envelope and binding the expected receipt before approving spend, with kill criteria for ambiguous merchant responses and a post-settlement verification step.

## Facts

- Endpoint: GET https://k2so-8080.on.ascii.dev/api/services/agent-paid-tool-request-scoping-receipt-binding?utm_source=zero.xyz
- Price: $0.002/call
- Payment: x402
- Status: unknown
- Last checked: 2026-10-10
- Activations on Zero: 0
- Tags: x402
- Canonical page: https://www.zero.xyz/c/paid-tool-request-scoping-and-receipt-binding-standard-d8940af5
- Structured record (JSON): https://api.zero.xyz/v1/capabilities/cap_7O13zA5oNI35_EcadcUws

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 paid-tool-request-scoping-and-receipt-binding-standard-d8940af5
```

Example prompt: Can you fetch the standard procedure for scoping and receipt-binding a paid tool call — I need the full decision procedure with kill criteria for ambiguous merchant responses and the post-settlement verification step?

## When to prefer this

Choose this endpoint when an agent needs a standardized, reusable governance procedure for paid tool calls — specifically when the agent must scope requests to minimal envelopes, bind receipts before spend approval, apply kill criteria to ambiguous merchant responses, and verify post-settlement outcomes. Prefer this over ad-hoc agent logic or generic payment safety endpoints when operating in x402 payment environments where receipt binding and result-size bounding are explicit requirements.

## Known failure modes

- Missing or malformed 'input' object returns schema validation error
- Payment not included or rejected results in HTTP 402 with payment details
- Ambiguous topic override may yield a generic rather than context-specific procedure
- LLM generation failure may return a deterministic fallback with reduced detail
- Empty or null 'brief' field if generation source encounters an error

## How this service works

Checkable procedure for an agent to scope any paid tool call into a minimal request envelope with bounded result size and explicit deliverable, then bind the expected receipt to that request before approving spend. Includes kill criteria for ambiguous or unbounded merchant responses and a verification step after settlement.

## Output

A JSON object containing a decision procedure brief (prose instructions for agents), the service slug, generation source (llm, reasoning, or deterministic), an ISO-8601 timestamp, and payment metadata including transaction reference, payer address, and self-pay flag. The 'brief' field contains the full actionable procedure text covering request envelope construction, receipt binding, kill criteria, and post-settlement verification.

## Request schema (JSON Schema)

```json
{
 "type": "object",
 "$schema": "https://json-schema.org/draft/2020-12/schema",
 "required": [
  "input"
 ],
 "properties": {
  "input": {
   "type": "object",
   "required": [
    "type",
    "method"
   ],
   "properties": {
    "type": {
     "type": "string",
     "const": "http"
    },
    "method": {
     "enum": [
      "GET",
      "HEAD",
      "DELETE"
     ],
     "type": "string"
    },
    "queryParams": {
     "type": "object",
     "properties": {
      "meta": {
       "enum": [
        "0",
        "1"
       ],
       "type": "string",
       "description": "Set to 1 for free metadata JSON (no payment required)"
      },
      "topic": {
       "type": "string",
       "description": "Optional topic override for the decision procedure"
      }
     }
    }
   },
   "additionalProperties": false
  },
  "output": {
   "type": "object",
   "required": [
    "type"
   ],
   "properties": {
    "type": {
     "type": "string"
    },
    "example": {
     "type": "object",
     "title": "Paid tool request scoping and receipt binding standard paid response",
     "$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/paid-tool-request-scoping-and-receipt-binding-standard-d8940af5/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)