IntentFence x402 Quote Verifier

x402

IntentFence x402 Quote Verifier is a paid API for AI agents from agentpass-protocol.rmalka06.chatgpt.site, paid per call via x402, $0.002/call, status unknown (last checked 2026-10-11).

Probes a target x402-gated URL and verifies whether the payment quote is safe to pay — checking asset type, price ceiling, payee address, and resource binding before an agent commits funds.

Price / call$0.002

Seller volume →—

Success—

StatusUnknown

How this service works

Fail-closed, action-bound authorization for AI agents with five-minute ES256 receipts, MCP risk scanning, and x402 payment safety.

Output

Returns a JSON object with a 'status' field (e.g. 'ready'), an 'intentfence' confidence score (0–1), the observed HTTP status code, whether a 402 Payment Required was present and if redirects were blocked, a verification tier indicating how the assessment was performed, and a signed receipt confirming live endpoint readiness.

Example use cases

Pre-payment safety check for autonomous agent

“My agent is about to pay an x402 endpoint at https://api.weatherservice.io/premium-forecast — before it spends any USDC, verify that the quoted price is under $0.05, the payee is 0x1234567890abcdef1234567890abcdef12345678, and it's genuinely a Base USDC charge. Give me a green light or flag it.”

Enforce price ceiling across marketplace APIs

“I'm integrating with a third-party x402 API at https://marketplace.example.com/data/prices and I need you to check that they won't charge more than $0.50 USDC per call — probe the endpoint and tell me if it passes my max price policy.”

Detect redirect or spoofing risk before payment

“Can you check whether https://pay.suspiciousapi.xyz/premium actually presents a proper x402 payment challenge without any redirect tricks, and tell me the intentfence confidence score so I can decide whether to trust it?”

Technical details

Endpoint

POSThttps://agentpass-protocol.rmalka06.chatgpt.site/api/x402-readiness?utm_source=zero.xyz

When to prefer

Use IntentFence when an AI agent is about to execute an x402 micropayment and needs an independent, caller-side verification that the quote is legitimate — especially when payee address whitelisting, price ceiling enforcement, or redirect-spoofing detection is required. Prefer this over blindly trusting the payment challenge returned by the target server itself.

Side effects

Target URL is not reachable or returns non-402 status — status reflects endpoint not x402-ready
Price exceeds max_price_usdc — returns a non-ready status flagging the price violation
Payee address not in allowed_payees allowlist — returns ready_with_review or rejected status
Target URL uses non-HTTPS or non-standard port — rejected as invalid input
Malformed payee address (not valid 0x hex) — input validation error
URL exceeds 2048 character limit — request rejected
POST body exceeds 4096 encoded bytes — input validation error

Input

Schema · Request body

Field	Type	Description
body	—	Optional JSON request body for POST probes, limited to 4096 encoded bytes.
method	string
policy	object	Legacy nested policy input. New buyers should use the optional top-level fields.
subject	string	Optional buyer identifier. Omit for anonymous marketplace delivery.
target_url	string	Public HTTPS x402 resource URL on the standard HTTPS port.
allowed_payees	array	Optional explicit payee allowlist. Omission yields ready_with_review for an otherwise valid quote.
max_price_usdc	string	Optional maximum acceptable x402 price in USDC.

Output

Schema · Response

{
  "type": "json",
  "example": {
    "status": "ready",
    "receipt": {
      "signed": true,
      "assurance": "live-x402-endpoint-readiness"
    },
    "observed": {
      "http_status": 402,
      "redirect_blocked": false,
      "payment_required_present": true
    },
    "request_id": "7d7fbf44-3c39-4eca-89d6-b44d756c8df1",
    "intentfence": "0.9",
    "verification_tier": "live-x402-readiness+x402-settled"
  }
}

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