Token Safety Check MCP Server

token-safety-check

Is this token safe? A rug check for any token on Base, Ethereum, Arbitrum, Optimism, Polygon or Solana, for AI agents and scripts. Each check returns:

• a 0–100 risk score and level (low, medium, high, critical) with plain-language reasons:
  • who can mint, freeze, blacklist, pause or change fees
  • upgradeable contract code
  • Token-2022 permanent delegates, transfer fees and hooks
  • holder concentration
  • thin or missing liquidity
  • a deployer whose earlier tokens lost their liquidity, or who launches tokens in bulk
• the facts behind the score: owner, authorities, supply, top holders, pools, and the deployer's launch record when we saw the token launch;
• USD price and liquidity;
• a fingerprint. Pass it back as since and the next check tells you what changed: new risks, authority changes, liquidity or price moves. That makes it easy to monitor tokens on a schedule.

A watchlist call re-checks up to 5 tokens at once for the same $0.01, returning a compact entry per token and one-line alerts for whatever changed since your last call.

Checks and watchlist calls cost $0.01 each in USDC on Base, paid automatically with x402 from a wallet you control. There's no account or API key. Errors and invalid input are never charged, and a spending cap stops any call priced above your limit (default $0.05).

The score is rules-based and is not investment advice. Powers count for less on tokens with deep liquidity, where they're usually a large issuer's compliance controls (USDC can freeze and mint, for example).

Use it from Claude Desktop, Cursor or any MCP client

Create a new wallet just for this and send it a little USDC on Base: $1 covers 100 checks. Then add to your MCP config (for Claude Desktop, that's claude_desktop_config.json):

{
  "mcpServers": {
    "token-safety-check": {
      "command": "npx",
      "args": ["-y", "token-safety-check"],
      "env": { "X402_PRIVATE_KEY": "0x<private key of the dedicated wallet>" }
    }
  }
}

The server has two tools:

• check_token_safety (address, optional chain and since): the full check for one token.
• watch_tokens (tokens: up to 5 of { address, chain?, since? }): re-checks them all in one paid call and, given each token's earlier fingerprint, reports what changed with one-line alerts.

Optional environment variables:

• TOKEN_SAFETY_MAX_USD: per-check spending cap, default 0.05.
• TOKEN_SAFETY_ENDPOINT: point at another deployment.

Use it from code

npm install token-safety-check

import { createTokenSafetyClient } from "token-safety-check";

const client = createTokenSafetyClient({ privateKey: process.env.X402_PRIVATE_KEY as `0x${string}` });

const first = await client.checkToken({ chain: "base", address: "0x4ed4E862860beD51a9570b96d89aF5E1B0Efefed" });
console.log(first.risk.score, first.risk.level, first.risk.summary);
// 15 low Low risk: the owner can pause all transfers; ownership is not renounced.

// Later: what changed since then?
const later = await client.checkToken({ address: first.address, chain: "base", since: first.watch.fingerprint });
if (later.watch.changes?.anythingChanged) console.log(later.watch.changes);

Watch what you hold

let list = [
  { chain: "base", address: "0x4ed4E862860beD51a9570b96d89aF5E1B0Efefed" },
  { chain: "solana", address: "JUPyiwrYJFskUPiHa7hkeR8VUtAeFoSYbKedZNsDvCN" },
] as const;
let fingerprints: (string | undefined)[] = [];

// Every hour (or however often): one $0.01 call for the whole list.
const w = await client.watchlist(list.map((t, i) => ({ ...t, since: fingerprints[i] })));
for (const alert of w.alerts) console.log(alert); // e.g. "PEPINA (eth): risk 0 -> 30 (medium); liquidity -99.99%"
fingerprints = w.tokens.map((t) => t.fingerprint);

Use it in Coinbase AgentKit

import { customActionProvider } from "@coinbase/agentkit";
import { z } from "zod";
import { createTokenSafetyClient } from "token-safety-check";

const safety = createTokenSafetyClient({ privateKey: process.env.X402_PRIVATE_KEY as `0x${string}` });

export const tokenSafety = customActionProvider({
  name: "check_token_safety",
  description: "Rug check a token on Base, Ethereum, Arbitrum, Optimism, Polygon or Solana: 0-100 risk score with reasons.",
  schema: z.object({
    address: z.string().describe("Token contract or Solana mint address"),
    chain: z.enum(["base", "eth", "arbitrum", "optimism", "polygon", "solana"]).optional(),
  }),
  invoke: async (args) => JSON.stringify(await safety.checkToken(args)),
});
// Add tokenSafety to the actionProviders you pass to AgentKit.from(...).

Use it in LangChain (JS)

import { tool } from "@langchain/core/tools";
import { z } from "zod";
import { createTokenSafetyClient } from "token-safety-check";

const safety = createTokenSafetyClient({ privateKey: process.env.X402_PRIVATE_KEY as `0x${string}` });

export const checkTokenSafety = tool(async (args) => JSON.stringify(await safety.checkToken(args)), {
  name: "check_token_safety",
  description: "Rug check a token on Base, Ethereum, Arbitrum, Optimism, Polygon or Solana: 0-100 risk score with reasons.",
  schema: z.object({
    address: z.string(),
    chain: z.enum(["base", "eth", "arbitrum", "optimism", "polygon", "solana"]).optional(),
  }),
});

Example output (trimmed)

{
  "address": "0x4ed4E862860beD51a9570b96d89aF5E1B0Efefed",
  "chain": "base",
  "name": "Degen",
  "symbol": "DEGEN",
  "risk": {
    "score": 15,
    "level": "low",
    "reasons": [
      { "code": "can-pause", "points": 10, "text": "The owner can pause all transfers." },
      { "code": "owner-not-renounced", "points": 5, "text": "Ownership is not renounced." }
    ],
    "summary": "Low risk: the owner can pause all transfers; ownership is not renounced."
  },
  "market": { "dex": "uniswap-v3", "pairedWith": "WETH", "priceUsd": 0.000963, "quoteSideLiquidityUsd": 134000 },
  "watch": { "fingerprint": "eyJzIjoxNSwi…", "changes": null }
}

Without this package

Both are plain x402 endpoints, so any x402 client can call them directly: GET https://onchaincheck.dev/token?chain=<chain>&address=<address>[&since=<fingerprint>] and GET https://onchaincheck.dev/watchlist?tokens=<chain>:<address>,...[&since=<fp>,...]. It's also listed in the x402 Bazaar.

Safety notes

• Use a dedicated wallet with a small balance. The key never leaves your machine; it only signs USDC payments of the quoted price.
• Each check's price is read from the server's payment request before paying, and anything above maxUsdPerCheck / TOKEN_SAFETY_MAX_USD is refused.

MIT licensed.