B20 activation check

Is B20 live on Base mainnet? Send GET /api/b20-activation-check with no required fields (1 optional) and pay $0.002 per call over x402 or MPP (there is no free tier). It returns a JSON object with registry and features.

Queries the Activation Registry precompile for base.b20_asset and base.b20_stablecoin (or a custom feature id). Honest pre-launch too: reports not-activated until the registry flips. ?feature=base.b20_asset (optional)

Category: Payments & x402 · Tags: b20 base activation registry token-standard precompile

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Parameters

Example request

curl -i "https://agent402.tools/api/b20-activation-check"

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

Example response

{
  "registry": "0x8453000000000000000000000000000000000001",
  "features": [
    {
      "feature": "base.b20_asset",
      "featureId": "0xcdcc…",
      "activated": false
    }
  ]
}

From an MCP client

catalog.call {
  "slug": "b20-activation-check",
  "params": {}
}

The hosted connector at https://agent402.tools/mcp needs a payment for b20-activation-check; 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 (Authorization: Bearer a402_...) also pays it.
• A POST with a JSON body to /api/b20-activation-check 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-activation-check");

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