Known-address label lookup

Label a known EVM address from a curated, committed dataset: major stablecoin + token contracts (the USDC and USDG contracts of every EVM chain we settle on, USDC on Ethereum, USDT, DAI, WETH, WBTC), DEX routers (Uniswap, 1inch, 0x), canonical L1↔L2 bridges, large exchange hot/cold wallets, and burn/system addresses. Send POST /api/address-label with the required field address and pay $0.002 per call over x402 or MPP, or call it free by solving a proof-of-work challenge. It returns a JSON object with address, found, labels and provenance.

Deterministic and offline - the provenance field states the dataset revision. Unknown addresses return {found:false}, not an error.

Category: Crypto & onchain data · Tags: crypto address label exchange bridge router token evm

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Parameters

Example request

curl -i -X POST https://agent402.tools/api/address-label \
  -H "Content-Type: application/json" \
  -d '{"address":"0x833589fCD6eDb6E08f4c7C32D4f71b54bdA02913"}'

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

Example response

{
  "address": "0x833589fcd6edb6e08f4c7c32d4f71b54bda02913",
  "found": true,
  "labels": [
    {
      "label": "USDC",
      "category": "token",
      "network": "base",
      "note": "Circle USD Coin (native)"
    }
  ],
  "provenance": {
    "source": "curated in-repo dataset",
    "updated": "2026-10-02",
    "entries": 39
  }
}

From an MCP client

catalog.call {
  "slug": "address-label",
  "params": {
    "address": "0x833589fCD6eDb6E08f4c7C32D4f71b54bdA02913"
  }
}

On the hosted connector at https://agent402.tools/mcp, catalog.call runs address-label free (rate-limited, no wallet). Local install: npx -y agent402-mcp.

Errors and behavior

• address is required. An input the tool rejects returns an HTTP 4xx whose body carries error, tool, expected, required and example, so the caller can correct it.
• 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.
• Free tier: no outbound network call leaves the server for this tool, so proof-of-work (16 leading zero bits of sha256) pays for it.
• A GET or HEAD to /api/address-label returns the same 402 quote, so the price can be read without a body.
• 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/address-label", {
  method: "POST",
  headers: { "Content-Type": "application/json" },
  body: JSON.stringify({
    "address": "0x833589fCD6eDb6E08f4c7C32D4f71b54bdA02913"
  }),
});

No wallet? Pay with compute

Fetch a challenge, solve the sha256 puzzle (16 leading zero bits, a fraction of a second of CPU), and resend with the X-Pow-Solution header:

import { createHash } from "node:crypto";
const lz = (b) => { let t = 0; for (const x of b) { if (!x) { t += 8; continue; } t += Math.clz32(x) - 24; break; } return t; };
const c = await (await fetch("https://agent402.tools/api/pow/challenge?slug=address-label")).json();
let n = 0;
while (lz(createHash("sha256").update(c.challenge + ":" + n).digest()) < c.difficulty) n++;
await fetch("https://agent402.tools/api/address-label", { method: "POST", headers: { "X-Pow-Solution": c.token + ":" + n, "Content-Type": "application/json" }, body: JSON.stringify({"address":"0x833589fCD6eDb6E08f4c7C32D4f71b54bdA02913"}) });

Part of these workflows

Known-address label lookup is one step in these 2 skill packs, each sold as a single call:

• Contract audit - Triage a smart contract before an agent interacts with it: verified Solidity source, heuristic vulnerability scan, known-address check, function-selector resolution, and a read-only dry-run of the exact call you plan to make.
• Transaction forensics - Explain what an EVM transaction actually did: confirmation status, the raw transaction from the chain, decoded calldata with typed parameters, the resolved function signature, and labeled counterparties.

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