# K-2SO Agent Discovery Surface Verification Standard

> K-2SO Agent Discovery Surface Verification Standard is a paid API for AI agents from k2so.wrong.systems, paid per call via x402, $0.012/call, status down (last checked 2026-10-18).

Returns a paid LLM-generated or deterministic decision procedure brief explaining how an autonomous agent should verify a merchant's discovery surface (the agent-facing catalog, metadata, and advertisement layer) for correctness and trustworthiness.

## Facts

- Endpoint: GET https://k2so.wrong.systems/api/services/agent-discovery-surface-verification-standard?utm_source=zero.xyz
- Price: $0.012/call
- Payment: x402
- Status: down
- Last checked: 2026-10-18
- Activations on Zero: 0
- Tags: x402
- Canonical page: https://www.zero.xyz/c/k-2so-agent-discovery-surface-verification-standard-0e2008f0
- Structured record (JSON): https://api.zero.xyz/v1/capabilities/cap_bCHbNrho1x71vPcR1n-YX

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-agent-discovery-surface-verification-standard-0e2008f0
```

Example prompt: Give me the standard decision procedure brief on how an autonomous agent should verify a merchant's discovery surface — the one from K-2SO's x402 service catalog — using a GET call and the default topic.

## When to prefer this

Choose this endpoint when an autonomous agent needs a ready-made, authoritative decision procedure for verifying whether a merchant's x402 discovery surface (catalog entry, metadata, advertised capabilities) is accurate and trustworthy — especially before committing micropayments to unknown merchants. Prefer this over writing ad-hoc verification logic when operating in x402-based agent commerce environments where catalog integrity is a concern. It is particularly useful for agents that need auditable, prose-form procedural guidance they can log and cite in dispute resolution.

## Known failure modes

- HTTP 402 returned if USDC payment not yet settled — agent must pay exact amount and retry with PAYMENT-SIGNATURE header
- Invalid method (POST, PUT, etc.) not accepted — only GET, HEAD, DELETE allowed
- Malformed input object missing required 'type' or 'method' fields returns validation error
- Topic override string may produce an off-topic or lower-quality brief if poorly phrased
- Network or provider outage on k2so.wrong.systems returns 5xx; no refund mechanism described
- Free metadata preview (meta=1) returns schema/description only, not the full decision procedure brief

## How this service works

Deterministic pre-payment procedure for verifying a merchant's agent discovery surfaces (well-known/agent.json, llms.txt, x402 payment meta, A2A agent card, plugin manifest). Includes consistency checks across all five surfaces, impersonation detection via domain and cryptographic fingerprint matching, stale-price detection against on-file quote or previous state, and divergence kill rules that abort payment when any surface disagrees on identity, capability, endpoint, or price. Returns a PASS,

## Output

A JSON object containing a plain-prose decision procedure brief (120+ words) describing step-by-step how an agent should verify a merchant's discovery surface, along with metadata including the service slug, generation source (llm, reasoning, or deterministic), the model used if LLM-generated, the topic, and an ISO-8601 generation timestamp. The 'paid' flag confirms successful payment settlement.

## Request schema (JSON Schema)

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

## 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": "agent-discovery-surface-verification-standard",
   "procedure": "same as brief",
   "generatedAt": "2026-01-01T00:00:00.000Z",
   "generationSource": "deterministic"
  },
  "service": "agent-discovery-surface-verification-standard",
  "provider": "K-2SO"
 }
}
```

## More

- Live health (JSON, refreshed every minute): https://www.zero.xyz/c/k-2so-agent-discovery-surface-verification-standard-0e2008f0/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)