Stablecoin peg monitor

Live $1-peg deviation for the top USD stablecoins (USDT, USDC, USDS, DAI, USDe, PYUSD, USDD, TUSD, FDUSD by default, or pass your own list): current price, deviation in basis points, 24h high/low, worst 24h deviation, market cap, and an on-peg / stressed / depegged status. Send GET /api/stablecoin-peg with no required fields (1 optional) and pay $0.003 per call over x402 or MPP (there is no free tier). It returns a JSON object with peg, count and coins.

Backed by CoinGecko's public API.

Category: Crypto & onchain data · Tags: crypto stablecoin peg usdt usdc risk monitoring

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Parameters

Example request

curl -i "https://agent402.tools/api/stablecoin-peg"

Without payment this returns HTTP 402 Payment Required with the exact price for stablecoin-peg; any x402 v2 or MPP client pays it and retries.

Example response

{
  "peg": "USD $1.00",
  "count": 2,
  "coins": [
    {
      "id": "tether",
      "symbol": "USDT",
      "name": "Tether",
      "price": 0.998868,
      "deviationBps": -11.32,
      "high24h": 0.999372,
      "low24h": 0.998674,
      "maxDeviation24hBps": 13.26,
      "marketCap": 184092462233,
      "status": "on-peg"
    },
    {
      "id": "usd-coin",
      "symbol": "USDC",
      "name": "USDC",
      "price": 0.999819,
      "deviationBps": -1.81,
      "high24h": 0.999923,
      "low24h": 0.99953,
      "maxDeviation24hBps": 4.7,
      "marketCap": 73033499074,
      "status": "on-peg"
    }
  ]
}

From an MCP client

catalog.call {
  "slug": "stablecoin-peg",
  "params": {}
}

The hosted connector at https://agent402.tools/mcp needs a payment for stablecoin-peg; the stdio package pays it from a wallet or from AGENT402_CREDITS_KEY. Local install: npx -y agent402-mcp.

Errors and behavior

• Every field is optional. An input the tool rejects returns an HTTP 4xx whose body carries error, tool, expected, required and example.
• A paid call that ends in any status of 400 or above is not charged over x402, MPP or a prepaid credits key: settlement is cancelled when the tool fails. The exception is a Tempo push credential, a transfer the buyer sent before the call: it settles before the tool runs, so if the tool then fails the payment is recorded as a refund owed to the paying wallet.
• Wallet-only: this tool reaches the network or stored state, so it has no proof-of-work tier. A prepaid card-credits key issued earlier (Authorization: Bearer a402_...) also pays it.
• A POST with a JSON body to /api/stablecoin-peg is served as this GET, with the body as the input.
• An Idempotency-Key header makes a retried paid call replay the first 200 instead of charging again (an answer larger than 1 MB is not replayed).

Paid call (JavaScript agent)

import { wrapFetchWithPayment } from "@x402/fetch";
import { x402Client } from "@x402/core/client";
import { registerExactEvmScheme } from "@x402/evm/exact/client";
import { privateKeyToAccount } from "viem/accounts";

const client = new x402Client();
client.setSpendControls?.(false); // keep your own spending ceiling in code
registerExactEvmScheme(client, { signer: privateKeyToAccount(KEY) });
const payFetch = wrapFetchWithPayment(fetch, client);

const res = await payFetch("https://agent402.tools/api/stablecoin-peg");

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