# X402-MPP Paywall Verifier

> X402-MPP Paywall Verifier is a paid API for AI agents from mcp-gateway.agentdiet.dev, paid per call via x402, $0.01/call, status unknown (last checked 2026-10-22).

Verifies whether a given URL is protected by an x402/MPP paywall and returns structured proof of the paywall status including compression ratio metadata.

## Facts

- Endpoint: GET https://mcp-gateway.agentdiet.dev/v1/x402-mpp-paywall-verifier?utm_source=zero.xyz
- Price: $0.01/call
- Payment: x402
- Status: unknown
- Last checked: 2026-10-22
- Activations on Zero: 0
- Tags: x402
- Canonical page: https://www.zero.xyz/c/x402-mpp-paywall-verifier-a57bb107
- Structured record (JSON): https://api.zero.xyz/v1/capabilities/cap_jbFXvZLbw2ASTHjxQ03Nv

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 x402-mpp-paywall-verifier-a57bb107
```

Example prompt: Can you check if the URL https://api.example.com/data is protected by an x402 or MPP paywall — use a GET method and tell me the verification status and any ROI proof you get back?

## When to prefer this

Use this endpoint when an AI agent needs to programmatically detect whether a target URL is protected by an x402, MPP, or L402 paywall before attempting to access or pay for it. Prefer this over manual inspection when building automated agent workflows that must decide whether to route a micropayment prior to fetching a resource.

## Known failure modes

- Missing or invalid 'url' query parameter returns an error or empty data object
- URL not reachable or returning non-402 response may yield inconclusive verification
- Invalid HTTP method enum value (anything other than GET or POST) causes schema validation failure
- Malformed input object missing required 'type' or 'method' fields results in rejection
- USDC payment failure on Base network prevents endpoint access entirely

## How this service works

Deterministic B2A/A2A/MCP/x402/MPP/L402 execution and intelligence node at https://mcp-gateway.agentdiet.dev settling in USDC on Base.

## Output

Returns a JSON object with a 'status' field (e.g. 'ok'), a 'data' object containing paywall details, and a 'roi_proof' object including a 'compression_ratio_pct' value indicating the paywall's efficiency metrics. A status of 'ok' confirms successful 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",
      "POST"
     ],
     "type": "string"
    },
    "queryParams": {
     "type": "object",
     "properties": {
      "url": {
       "type": "string"
      }
     }
    }
   },
   "additionalProperties": false
  },
  "output": {
   "type": "object",
   "required": [
    "type"
   ],
   "properties": {
    "type": {
     "type": "string"
    },
    "example": {
     "type": "object"
    }
   }
  }
 }
}
```

## Response schema (JSON Schema)

```json
{
 "type": "json",
 "example": {
  "data": {},
  "status": "ok",
  "roi_proof": {
   "compression_ratio_pct": 91.4
  }
 }
}
```

## More

- Live health (JSON, refreshed every minute): https://www.zero.xyz/c/x402-mpp-paywall-verifier-a57bb107/health.json
- [Zero catalog index](https://www.zero.xyz/llms.txt)
- [Other services from mcp-gateway.agentdiet.dev](https://www.zero.xyz/host/mcp-gateway.agentdiet.dev/llms.txt)