Onchain SQL (query Base with SQL)

Run read-only SQL against Coinbase's indexed, DECODED blockchain data - base.events (decoded logs with parameters), base.transactions, base.blocks, base.decoded_user_operations, base.transaction_attributions (builder codes), plus solana.instructions and hyperevm.events. Send POST /api/onchain-sql with the required field sql and pay $0.020 per call over x402 or MPP (there is no free tier). It returns a JSON object with rows and rowCount.

ClickHouse-dialect SELECTs, server-side grammar validation, up to 50k rows / 30s / 12 joins. Ask Base anything - token flows, event analytics, gas studies - in one call, no indexer to run.

Category: Wallet operations · Tags: cdp coinbase wallet onboarding x402 agent-wallet sql analytics

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Parameters

Example request

curl -i -X POST https://agent402.tools/api/onchain-sql \
  -H "Content-Type: application/json" \
  -d '{"sql":"SELECT COUNT(*) AS txs FROM base.transactions WHERE block_number > 0 LIMIT 1"}'

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

Example response

{
  "rows": [
    {
      "txs": 123456
    }
  ],
  "rowCount": 1
}

From an MCP client

catalog.call {
  "slug": "onchain-sql",
  "params": {
    "sql": "SELECT COUNT(*) AS txs FROM base.transactions WHERE block_number > 0 LIMIT 1"
  }
}

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

Errors and behavior

• sql 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: settlement is cancelled when the tool fails.
• 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 GET or HEAD to /api/onchain-sql 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.

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/onchain-sql", {
  method: "POST",
  headers: { "Content-Type": "application/json" },
  body: JSON.stringify({
    "sql": "SELECT COUNT(*) AS txs FROM base.transactions WHERE block_number > 0 LIMIT 1"
  }),
});

Part of these workflows

Onchain SQL (query Base with SQL) is one step in this skill pack, each sold as a single call:

• Onchain analyst (SQL over Base) - Ask Base anything in one paid call: your SQL runs against Coinbase's indexed, DECODED chain data (events with parsed parameters, transactions, blocks, user-ops) with the live schema alongside - no indexer, no RPC archaeology.

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