Gas price

Current gas price on Base, Polygon, Arbitrum, Optimism, Ethereum, Monad, Celo, Avalanche, Sei, or Robinhood Chain - for an agent budgeting a transaction: returns network, gasPriceGwei and gasPriceWei (decimal strings) from the chain's own eth_gasPrice, the node's suggested all-in price per gas unit. Send GET /api/gas-estimate with no required fields (1 optional) and pay $0.001 per call over x402 or MPP (there is no free tier). It returns a JSON object with network, gasPriceGwei and gasPriceWei.

Multiply by the gas a transaction uses (21000 for a plain transfer) for its fee. Read-only. ?network=base

Category: Payments & x402 · Tags: gas gas-price fees gwei multichain robinhood usdg · Also found as: estimate-gas eth_estimategas

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Parameters

Example request

curl -i "https://agent402.tools/api/gas-estimate?network=base"

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

Example response

{
  "network": "base",
  "gasPriceGwei": "0.0051",
  "gasPriceWei": "5100000"
}

From an MCP client

catalog.call {
  "slug": "gas-estimate",
  "params": {
    "network": "base"
  }
}

The hosted connector at https://agent402.tools/mcp needs a payment for gas-estimate; 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.
• Cached: an identical request within 30s is answered from cache with X-Cache: hit.
• A POST with a JSON body to /api/gas-estimate 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/gas-estimate?network=base");

Part of these workflows

Gas price is one step in these 3 skill packs, each sold as a single call:

• Macro dashboard refresh - The full macro + crypto dashboard in one call: 5 FRED series, 5 Treasury reads, yield-curve spread, crypto market/trending/global, and live gas - the 14-tool basket recurring buyers refresh every cycle, bundled below its a la carte price.
• Cheapest rail right now - Where should an agent transact this minute? Live gas on Ethereum + every major L2 side by side, Base gas tiers, a fee estimate for your transaction type, and ETH spot to price it all in dollars.
• Gas optimizer - Find the cheapest gas right now: Base gas, Ethereum gas, Base fee estimate, and ETH price for USD conversion.

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