# MCP Tool Dynamic Discovery Payment Authorization Gate

> MCP Tool Dynamic Discovery Payment Authorization Gate is a paid API for AI agents from k2so.wrong.systems, paid per call via x402, $0.002/call, status down (last checked 2026-09-15).

Returns a blunt decision procedure for agents to authorize or deny the first paid x402 call when a new MCP tool is discovered mid-session

## Facts

- Endpoint: GET https://k2so.wrong.systems/api/services/mcp-tool-dynamic-discovery-payment-authorization
- Price: $0.002/call
- Payment: x402
- Status: down
- Last checked: 2026-09-15
- Activations on Zero: 0
- Tags: x402
- Canonical page: https://www.zero.xyz/c/mcp-tool-dynamic-discovery-payment-authorization-gate-6dc999c1
- Structured record (JSON): https://api.zero.xyz/v1/capabilities/cap_VQx4yEg_0ZKZ42IVL9DMN

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 mcp-tool-dynamic-discovery-payment-authorization-gate-6dc999c1
```

Example prompt: Give me a blunt decision procedure I can follow right now to decide whether to authorize the first x402 payment call for a new MCP tool I just discovered mid-session — I need clear go/no-go logic, not marketing.

## When to prefer this

Choose this endpoint when an AI agent needs a programmatic, opinionated decision procedure specifically for the MCP tool dynamic discovery scenario — i.e., an agent has encountered a new tool mid-session, read its schema, and must decide whether to authorize an x402 micropayment before any spend occurs. Prefer this over generic payment authorization guides when the context is specifically MCP tool discovery and x402 first-contact authorization.

## Known failure modes

- Missing or malformed input object returns schema validation error
- Invalid HTTP method (e.g. POST) rejected by enum constraint
- Service unavailable or provider error returns ok:false in result
- Payment authorization failure via x402 returns 402 before content delivery
- Empty or unsupported topic override may result in default topic being used

## How this service works

First-contact payment authorization for MCP tools discovered mid-session. When an agent's client lists an unknown tool and its first call demands x402 payment, this procedure gates the decision before any spend: deny-by-default, schema-to-challenge binding check, first-call spend cap, promote-to-allowlist after a clean first call, and re-verification when the schema drifts between sessions. Verdicts: AUTHORIZE_ONE, DENY, REVIEW_NEEDS_MANIFEST. Distinct from cost estimation: this gates first

## Output

A structured prose brief containing a blunt, step-by-step decision procedure for agents to evaluate and authorize or deny a first-contact x402 payment call from a newly discovered MCP tool. Includes the service slug, ISO-8601 generation timestamp, model used, generation source enum (llm/reasoning/deterministic), and the full procedure text. Payment metadata (payer, transaction) is also returned.

## Request schema (JSON Schema)

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

## More

- Live health (JSON, refreshed every minute): https://www.zero.xyz/c/mcp-tool-dynamic-discovery-payment-authorization-gate-6dc999c1/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)