Skill: Cheapest rail right now

Bundled execution of the Cheapest rail right now workflow — 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. One x402 payment runs 4 underlying tools (l2-gas-comparison, gas-snapshot, gas-estimate, crypto-price); partial-success per step.

Input

Example output

{
  "pack": "cheapest-rail",
  "args": {
    "networks": "ethereum,base,arbitrum,optimism,polygon"
  },
  "steps": [
    {
      "slug": "l2-gas-comparison",
      "ok": true,
      "result": {}
    },
    {
      "slug": "gas-snapshot",
      "ok": true,
      "result": {}
    },
    {
      "slug": "gas-estimate",
      "ok": true,
      "result": {}
    },
    {
      "slug": "crypto-price",
      "ok": true,
      "result": {}
    }
  ],
  "summary": "4/4 steps succeeded"
}

Try it — see the 402 challenge (free)

curl -i -X POST https://agent402.tools/api/skill/cheapest-rail \
  -H "Content-Type: application/json" \
  -d '{"networks":"ethereum,base,arbitrum,optimism,polygon"}'

The response is HTTP 402 Payment Required with exact payment requirements. Any x402 v2 client pays automatically and retries:

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();
registerExactEvmScheme(client, { signer: privateKeyToAccount(KEY) });
const payFetch = wrapFetchWithPayment(fetch, client);

const res = await payFetch("https://agent402.tools/api/skill/cheapest-rail", {
  method: "POST",
  headers: { "Content-Type": "application/json" },
  body: JSON.stringify({
    "networks": "ethereum,base,arbitrum,optimism,polygon"
  }),
});

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