presign-guard MCP server

presign-guard

A pre-sign risk check for AI agents. Before an agent signs a transaction, approval, or EIP-712 signature, it pays a few cents per call over x402 and gets back a green / orange / red verdict with machine-readable reason codes. Optionally, it also gets a plain-language explanation in Dutch or English.

Watch the 1-minute explainer: presign-guard.onrender.com/media/explainer.mp4

New: the token verdict in 45 seconds: presign-guard.onrender.com/media/token.mp4

Part of Klaartaal by FIZZL AI.

Endpoints

Payment is x402 v2 with the exact scheme, in USDC on Base (the token verdict also on Solana). The 402 carries Bazaar discovery metadata (input example, input and output schema), and the challenge is mirrored into the JSON body for clients that don't read the PAYMENT-REQUIRED header. You are never charged for an error. Invalid requests (400) and upstream outages (503) cancel settlement, and they always return verdict: null, never a guessed verdict.

MCP

https://presign-guard.onrender.com/mcp is an MCP server (Streamable HTTP, stateless) for Claude, Cursor and agent frameworks, listed in the official MCP registry as io.github.Fizzl13/presign-guard.

The paid tools are paid inside the MCP call with the x402 MCP transport (meta["x402/payment"]), on Base (tokenverdict also on Solana), to the same payout wallets as the HTTP routes. Invalid input is refused before payment, and a failed check is not charged.

Token verdict

GET /v1/token?chain=solana&address= (or chain=base|ethereum|arbitrum|optimism|polygon|bsc with a 0x token contract) answers one question before an agent buys, holds or accepts a token: is the token itself a trap?

{
  "verdict": "orange",
  "grade": "RISKY",
  "one_liner": "RISKY: 1% transfer fee; $21k liquidity; 1 h old (+2 more)",
  "reasons": [{ "code": "TRANSFER_FEE", "severity": "orange", "details": { "feePct": 1 } }, "…"],
  "token": { "chain": "solana", "address": "…", "name": "…", "symbol": "…" },
  "market": { "priceUsd": 0.0004, "liquidityUsd": 21000, "marketCapUsd": 400000, "volume24hUsd": 90000, "firstPairAt": "…", "ageSeconds": 3600, "url": "https://dexscreener.com/…" },
  "sources": ["goplus", "dexscreener", "rugcheck"],
  "checkedAt": "…"
}

Shortened. The full README is on GitHub.