x402check MCP server

x402check — pre-payment risk checks for x402 agents and wallets

LIVE: https://x402check.xyz · did:web:x402check.xyz · $0.001 per evaluation with prepaid credits, or per call via x402 ($0.0035 on Base; $0.005 with transaction simulation) · discovery · DID document · JWKS

x402check is an x402 risk-check provider (wire format of x402 PR #2422). You call it before an agent or a wallet pays or signs, and it checks the counterparty. It combines provider-verified evidence with a typed model:

• the OFAC SDN list, refreshed daily;
• curated phishing and drainer feeds;
• transaction simulation: where the assets actually go, and which approvals are granted;
• drainer-kit code fingerprints, which recognize redeployed drainer contracts before their address is listed;
• our own kit watch: every Ethereum and Base block is read as it is produced. It records look-alike wallets that delegate (EIP-7702) to an address-poisoning executor, wallets whose delegate forwards whatever they receive (sweepers), and new contracts running drainer-kit code;
• look-alike domain analysis;
• on-chain facts about the counterparty, such as whether an approval is being granted to a plain wallet;
• a typed model (TypeSafe Jev) that reads the content the agent acted on for injected instructions.

Every verdict is an ES256 attestation. It states which checks the provider actually ran and which fields the caller merely asserted.

Scope, stated plainly. x402check catches what the chain, the lists, its own kit watch, and the content in front of it reveal. It does not see laundering patterns or other transaction-graph behaviour. It cannot flag an unknown drainer address that is simply sent funds, unless the address is one of the look-alikes or compromised wallets the kit watch has seen. A clean verdict means "none of these checks fired", not "safe". Measured limits are in docs/EVIDENCE.md.

The demo video predates v0.2.0. Its evidence slide shows v5 corpus numbers that EVIDENCE.md supersedes, and it predates the v0.3 layers (simulation, code fingerprints) and pricing (every evaluation is paid; there is no free tier).

What it checks

Shortened. The full README is on GitHub.