# MCP Tool Cost Registry & Pre-Execution Per-Tool Cost Estimation Brief

> MCP Tool Cost Registry & Pre-Execution Per-Tool Cost Estimation Brief 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 paid decision-procedure brief for agents on how to maintain an MCP tool cost registry and estimate per-tool costs before execution on x402-paid tool servers

## Facts

- Endpoint: GET https://k2so.wrong.systems/api/services/mcp-tool-cost-registry-and-pre-execution-per-too
- 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-cost-registry-pre-execution-per-tool-cost-estimation-brief-778bccc5
- Structured record (JSON): https://api.zero.xyz/v1/capabilities/cap_jpDC6LBvRLgY7Kwld75Ur

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-cost-registry-pre-execution-per-tool-cost-estimation-brief-778bccc5
```

Example prompt: Give me the decision procedure for building an MCP tool cost registry and doing pre-execution per-tool cost estimation on x402-paid tool servers, including the browser-action payment receipt verification standard.

## When to prefer this

Choose this endpoint when an AI agent needs authoritative, actionable guidance — not generic documentation — on implementing a cost registry for MCP tools and gating tool execution by pre-estimated cost in x402 payment environments. Prefer it over static docs when you need a blunt, agent-optimized decision procedure that covers payment receipt verification standards and is generated fresh with a timestamp.

## Known failure modes

- Payment not received or insufficient — endpoint returns 402 with payment instructions
- Invalid method (POST/PUT not accepted — only GET/HEAD/DELETE)
- Topic override not recognized — may return generic procedure
- Service temporarily unavailable — 5xx response
- Meta=1 returns free metadata JSON but no decision procedure content

## How this service works

Paid agent-facing brief on MCP tool cost registry and pre-execution per-tool cost estimation for x402-paid tool servers; browser-action payment receipt verification standard-0. Blunt decision procedure, not marketing.

## Output

A structured JSON response containing a prose decision-procedure brief ('brief' field) tailored to MCP tool cost registry and pre-execution cost estimation for x402-paid tool servers, along with metadata including the service slug, topic, generation timestamp, generation source (llm/reasoning/deterministic), and payment confirmation details.

## Request schema (JSON Schema)

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

## More

- Live health (JSON, refreshed every minute): https://www.zero.xyz/c/mcp-tool-cost-registry-pre-execution-per-tool-cost-estimation-brief-778bccc5/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)