# Hermes Data API – Ethereum Gas Fees

> Hermes Data API – Ethereum Gas Fees is a paid API for AI agents from x402-api-blond.vercel.app, paid per call via x402, $0.01/call, status unknown (last checked 2026-09-15).

Returns current Ethereum network gas prices (fast, safe, and propose tiers in Gwei) sourced from Etherscan, paid per-call via x402/USDC.

## Facts

- Endpoint: POST https://x402-api-blond.vercel.app/eth/gas
- Price: $0.01/call
- Payment: x402
- Status: unknown
- Last checked: 2026-09-15
- Activations on Zero: 0
- Tags: x402
- Canonical page: https://www.zero.xyz/c/hermes-data-api-ethereum-gas-fees-2c3a381e
- Structured record (JSON): https://api.zero.xyz/v1/capabilities/cap_YVttIpxmnCwAejNqprUQ6

Status and success rate cover calls made through Zero and Zero's own probes. Third-party monitors may report differently.

## How to call it through Zero

Zero handles the 402 payment challenge and records the run. With the Zero CLI installed (`npm i -g @zeroxyz/cli`):

```sh
zero fetch --capability hermes-data-api-ethereum-gas-fees-2c3a381e -d '<json body>'
```

Example prompt: What's the current Ethereum gas price — give me the fast, safe, and propose Gwei tiers so I know what to set for my transaction right now?

## When to prefer this

Choose this endpoint when you need real-time Ethereum gas fee data in a pay-per-call, no-subscription model using USDC on Base via x402 protocol. Ideal for agents operating in crypto-native or DeFi contexts that already handle x402 payments and need fresh Gwei tiers (fast/safe/propose) without managing Etherscan API keys directly.

## Known failure modes

- Payment failure: x402 USDC payment on Base rejected or insufficient balance — endpoint returns 402 Payment Required
- Upstream Etherscan API unavailable — may return 503 or stale data
- Invalid MCP tool descriptor structure in request body — returns 400 Bad Request
- Network timeout fetching from Etherscan — delayed or error response

## How this service works

Pay-per-call data API: crypto prices (CoinGecko), China A-share quotes (Sina), weather (Open-Meteo), forex rates, and Ethereum gas fees. Payments via x402 protocol, USDC on Base.

## Output

A JSON object with a Unix millisecond timestamp, the data source ('etherscan'), and three Gwei values: fast_gwei (quick inclusion), safe_gwei (low-priority), and propose_gwei (standard recommended), e.g. {ts: 1750000000000, source: 'etherscan', fast_gwei: 0.083, safe_gwei: 0.07, propose_gwei: 0.074}.

## Request schema (JSON Schema)

```json
{
 "type": "object",
 "$schema": "https://json-schema.org/draft/2020-12/schema",
 "required": [
  "input"
 ],
 "properties": {
  "input": {
   "type": "object",
   "required": [
    "type",
    "toolName",
    "inputSchema"
   ],
   "properties": {
    "type": {
     "type": "string",
     "const": "mcp"
    },
    "example": {
     "type": "object"
    },
    "toolName": {
     "type": "string"
    },
    "description": {
     "type": "string"
    },
    "inputSchema": {
     "type": "object"
    }
   },
   "additionalProperties": false
  },
  "output": {
   "type": "object",
   "required": [
    "type"
   ],
   "properties": {
    "type": {
     "type": "string"
    },
    "example": {
     "type": "object"
    }
   }
  }
 }
}
```

## Response schema (JSON Schema)

```json
{
 "type": "json",
 "example": {
  "ts": 1750000000000,
  "source": "etherscan",
  "fast_gwei": 0.083,
  "safe_gwei": 0.07,
  "propose_gwei": 0.074
 }
}
```

## More

- Live health (JSON, refreshed every minute): https://www.zero.xyz/c/hermes-data-api-ethereum-gas-fees-2c3a381e/health.json
- [Zero catalog index](https://www.zero.xyz/llms.txt)
- [Other services from x402-api-blond.vercel.app](https://www.zero.xyz/host/x402-api-blond.vercel.app/llms.txt)