verify402 MCP server

verify402

Machine-payable on-chain truth & pre-signing checks for AI agents.

Free fail-closed preflight gate + five verifiable truth checks paid per call via x402 in USDC. No API key, no account, no wallet required for the free gate.

Demo scope: the public demo settles payments in Base Sepolia testnet USDC. The analysis itself reads mainnet chain data (Ethereum, Arbitrum, Base). This is not a mainnet payment service, and no testnet payment is mainnet revenue.

30-Second Quickstart

1. Free Preflight Gate (No wallet, no key)

Verify an x402 payment challenge before signing it:

curl -sS -X POST https://verify402.onrender.com/preflight \
  -H 'content-type: application/json' \
  -d '{
    "kind": "payment",
    "payment": {
      "scheme": "exact",
      "network": "eip155:84532",
      "asset": "0x036CbD53842c5426634e7929541eC2318f3dCF7e",
      "amount": "10000",
      "payTo": "0xAeEF086DD4e436c69d6d0F684b4c9F43392df9cb",
      "resource": "https://verify402.onrender.com/verify"
    },
    "policy": { "maxAmountUsd": 0.25, "allowedResourceHosts": ["verify402.onrender.com"] }
  }'

This example uses the public demo's Base Sepolia testnet USDC (eip155:84532), not mainnet. The free gate is only validating the request shape; it is not a payment. The paid analysis routes read mainnet chain data (Ethereum, Arbitrum, Base), but the demo does not settle mainnet payments.

Returns PASS / CAUTION / BLOCK, typed reasons, exact checked and notChecked lists, pinned block number, and a verifiable 90-second HMAC receipt.

A PASS means the listed checks passed at that block. It does not mean the transaction is safe or cannot drain funds, and the paid token check is a quote-based sellability check, not a honeypot proof. Read notChecked in the response.

Test the free gate (3 testers wanted)

I’m looking for three developers building AI agents, MCP tools, or x402 payment integrations to run 3–5 real intents and report what breaks. Demo payments use Base Sepolia testnet only; analysis reads mainnet chain data; no wallet or paid test is required.

• Run it in the browser — paste a token address, or run the raw intent; no terminal needed
• 5-minute testing guide
• Open a tester feedback issue
• Full onboarding notes

The most useful finding is a false PASS: an intent the gate allowed that you believe is unsafe.

🤖 Using verify402 with AI Agents (Step-by-Step)

The MCP server is live on npm as verify402-mcp and indexed on the official Model Context Protocol Registry (io.github.a32116150-ctrl/verify402-mcp).

It works with Claude Desktop, Cursor, Windsurf, Cline, OpenCode, and any MCP client over stdio.

Step 1: Add the MCP Server to Your Agent

Shortened. The full README is on GitHub.