B20 token info

ERC-20 metadata plus B20 signals for any Base address: name, symbol, decimals, total supply, best-effort paused/cap, bytecode size, and whether the address carries the factory-issued 0xB200 prefix. Send GET /api/b20-token-info with the required field address and pay $0.005 per call over x402 or MPP (there is no free tier). It returns a JSON object with address, isB20, prefixMatch, name, symbol and 3 more.

Works on plain ERC-20s too (isB20 comes back false). ?address=0x…

Category: Payments & x402 · Tags: b20 base erc20 token metadata supply

TRY IN PLAYGROUND →

Parameters

Example request

curl -i "https://agent402.tools/api/b20-token-info?address=0x833589fcd6edb6e08f4c7c32d4f71b54bda02913"

Without payment this returns HTTP 402 Payment Required with the exact price for b20-token-info; any x402 v2 or MPP client pays it and retries.

Example response

{
  "address": "0x8335…2913",
  "isB20": false,
  "prefixMatch": false,
  "name": "USD Coin",
  "symbol": "USDC",
  "decimals": 6,
  "totalSupply": "…",
  "totalSupplyFormatted": "…"
}

From an MCP client

catalog.call {
  "slug": "b20-token-info",
  "params": {
    "address": "0x833589fcd6edb6e08f4c7c32d4f71b54bda02913"
  }
}

The hosted connector at https://agent402.tools/mcp needs a payment for b20-token-info; the stdio package pays it from a wallet or from AGENT402_CREDITS_KEY. 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.
• Wallet-only: this tool reaches the network or stored state, so it has no proof-of-work tier. A prepaid card-credits key (Authorization: Bearer a402_...) also pays it.
• A POST with a JSON body to /api/b20-token-info 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/b20-token-info?address=0x833589fcd6edb6e08f4c7c32d4f71b54bda02913");

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