# @x402-api/mcp-server

<a href="https://glama.ai/mcp/servers/@fernsugi/x402-api">
  <img width="380" height="200" src="https://glama.ai/mcp/servers/@fernsugi/x402-api/badge" alt="x402-api MCP server" />
</a>

> MCP server that gives Claude, ChatGPT, and any MCP-compatible AI agent access to pay-per-call crypto/DeFi data via the [x402 protocol](https://github.com/coinbase/x402).

**8 tools. No API keys. AI agents pay USDC micropayments on Base, per request.**

**Find this service:** [Official MCP Registry](https://registry.modelcontextprotocol.io/?q=io.github.fernsugi%2Fx402-api) · [Glama](https://glama.ai/mcp/servers/fernsugi/x402-api-mcp-server) · [Agent discovery manifest](https://x402-api.fly.dev/.well-known/x402) · [OpenAPI](https://x402-api.fly.dev/openapi.json).

```
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   ╚═╝  ╚═╝     ╚═╝ ╚═════╝ ╚══════╝
```

## Tools

| Tool | API Endpoint | Cost | Description |
|------|-------------|------|-------------|
| `get_crypto_prices` | `GET /api/price-feed` | 0.001 USDC | BTC/ETH/SOL + top 24h movers |
| `get_gas_prices` | `GET /api/gas-tracker` | 0.001 USDC | Multi-chain gas (ETH, Base, Polygon, Arbitrum) |
| `get_dex_quotes` | `GET /api/dex-quotes` | 0.002 USDC | One ParaSwap aggregate route |
| `scan_token` | `GET /api/token-scanner` | 0.003 USDC | GoPlus security flags and heuristic |
| `track_whales` | `GET /api/whale-tracker` | 0.005 USDC | Top-holder sample and supply share |
| `scan_yields` | `GET /api/yield-scanner` | 0.005 USDC | DefiLlama pool APYs and TVL |
| `get_funding_rates` | `GET /api/funding-rates` | 0.008 USDC | Hyperliquid and dYdX hourly rates |
| `profile_wallet` | `GET /api/wallet-profiler` | 0.008 USDC | Observed Blockscout balances; partial coverage |

---

## Quick Start

### Option A: Inspect mode (no payment needed)

Just run it — any 402 responses will return human-readable payment instructions:

```bash
npx @x402-api/mcp-server
```

Claude will tell you what's needed when a tool requires payment.

### Option B: Auto-pay mode (fully autonomous)

Install optional payment deps and set your wallet key:

```bash
npm install -g @x402-api/mcp-server
npm install -g viem
export X402_WALLET_PRIVATE_KEY=0x<your_private_key>
x402-api-mcp
```

The MCP server signs Base USDC EIP-3009 authorizations only when the API advertises that settlement mode. The default payment cap is 0.01 USDC per call. Fund the wallet with USDC on Base; the API operator sponsors gas in direct settlement mode.

---

## Claude Desktop Integration

Add to your `claude_desktop_config.json`:

### Without auto-pay (inspect mode)

```json
{
  "mcpServers": {
    "x402-api": {
      "command": "npx",
      "args": ["@x402-api/mcp-server"]
    }
  }
}
```

### With auto-pay

```json
{
  "mcpServers": {
    "x402-api": {
      "command": "npx",
      "args": ["@x402-api/mcp-server"],
      "env": {
        "X402_WALLET_PRIVATE_KEY": "0x<your_private_key>"
      }
    }
  }
}
```

**Config file location:**
- macOS: `~/Library/Application Support/Claude/claude_desktop_config.json`
- Windows: `%APPDATA%\Claude\claude_desktop_config.json`
- Linux: `~/.config/Claude/claude_desktop_config.json`

---

## Environment Variables

| Variable | Required | Description |
|----------|----------|-------------|
| `X402_WALLET_PRIVATE_KEY` | Optional | Base wallet private key for EIP-3009 automatic payment. Requires `viem`. |
| `X402_MAX_PER_CALL_USDC` | Optional | Per-call cap, default `0.01` USDC. |
| `X402_API_BASE_URL` | Optional | Override API URL (default: `https://x402-api.fly.dev`) |

---

## How x402 Payments Work

This API uses the [x402 protocol](https://github.com/coinbase/x402) — HTTP 402 Payment Required:

1. **Agent calls tool** → MCP server makes API request
2. **Server returns 402** with payment details (amount, USDC address, Base network)
3. **Auto-pay mode:** this client signs an EIP-3009 authorization and retries; the API settles it on Base
4. **Inspect mode:** MCP returns 402 details without signing or paying

**Payment details:**
- Token: USDC on Base mainnet
- Address: `0x60264c480b67adb557efEd22Cf0e7ceA792DefB7`
- Chain: Base (chain ID 8453)
- Amount: 0.001–0.008 USDC per call (< 1 cent USD)

---

## Tool Reference

### `get_crypto_prices`
No parameters. Returns current prices for BTC, ETH, SOL + top 24h movers.

```
Cost: 0.001 USDC
```

### `get_gas_prices`
No parameters. Returns gas prices for Ethereum, Base, Polygon, Arbitrum — slow/standard/fast tiers.

```
Cost: 0.001 USDC
```

### `get_dex_quotes`
Get one ParaSwap aggregate route. No independent comparison between DEX venues.

| Parameter | Type | Required | Description |
|-----------|------|----------|-------------|
| `from` | string | ✅ | Input token (e.g. `"ETH"`, `"0x..."`) |
| `to` | string | ✅ | Output token (e.g. `"USDC"`) |
| `amount` | string | ✅ | Amount to swap (e.g. `"1.5"`) |

```
Cost: 0.002 USDC
```

### `scan_token`
Token security scan — detects rug-pull flags, honeypot patterns, mint authority, etc.

| Parameter | Type | Required | Description |
|-----------|------|----------|-------------|
| `token` | string | ✅ | Contract address or symbol (e.g. `"PEPE"`) |

```
Cost: 0.003 USDC
```

### `track_whales`
Top-holder sample from GoPlus. Gini and recent transfer history unavailable.

| Parameter | Type | Required | Description |
|-----------|------|----------|-------------|
| `token` | string | ✅ | Contract address or symbol |

```
Cost: 0.005 USDC
```

### `scan_yields`
Top DeFi yield opportunities across Aave, Compound, Morpho, Lido, Pendle, etc.

| Parameter | Type | Required | Description |
|-----------|------|----------|-------------|
| `chain` | string | ❌ | Filter by chain: `"ethereum"`, `"base"`, `"arbitrum"`, `"polygon"` |
| `min_tvl` | number | ❌ | Minimum TVL in USD (e.g. `1000000`) |

```
Cost: 0.005 USDC
```

### `get_funding_rates`
Hourly perpetual funding from Hyperliquid and dYdX v4. Spreads are indicative.

| Parameter | Type | Required | Description |
|-----------|------|----------|-------------|
| `asset` | string | ❌ | Asset symbol (e.g. `"BTC"`, `"ETH"`). All assets if omitted. |

```
Cost: 0.008 USDC
```

### `profile_wallet`
Observed priced wallet balances and available transaction counts. DeFi positions, PnL and risk score unavailable.

| Parameter | Type | Required | Description |
|-----------|------|----------|-------------|
| `address` | string | ✅ | Ethereum/Base wallet address (`0x...`) |

```
Cost: 0.008 USDC
```

---

## Development

```bash
git clone https://github.com/fernsugi/x402-api-mcp-server
cd x402-api-mcp-server

npm install
npm run build
npm start
```

To test without a payment wallet, simply run and see the 402 responses:

```bash
node dist/index.js
```

---

## Links

- [x402 API Landing Page](https://x402-api.fly.dev)
- [x402 Protocol](https://github.com/coinbase/x402)
- [Base Chain](https://base.org)
- [ERC-8004 Agent Identity](https://eips.ethereum.org/EIPS/eip-8004)
- [Agent #18763 on BaseScan](https://basescan.org/address/0x8004A169FB4a3325136EB29fA0ceB6D2e539a432)

---

## License

MIT

## Three runnable workflows

| Workflow | Tools | Total USDC |
|---|---|---:|
| [Token check](https://x402-api.fly.dev/demos/token-check.html?utm_source=github&utm_campaign=token-check) | `scan_token` + `track_whales` | 0.008 |
| [ETH funding](https://x402-api.fly.dev/demos/funding-compare.html?utm_source=github&utm_campaign=funding-compare) | `get_funding_rates` | 0.008 |
| [Swap quote + gas](https://x402-api.fly.dev/demos/swap-cost.html?utm_source=github&utm_campaign=swap-cost) | `get_dex_quotes` + `get_gas_prices` | 0.003 |

[Runnable Node examples](https://github.com/fernsugi/x402-api-server/tree/main/examples) start in inspect mode. Each demo has inputs, recorded provider output, coverage limits, a spending cap, and an agent prompt.

Optional `X402_REFERRAL_SOURCE` labels requests for first-party aggregate attribution (default `mcp`). It is a hint, not verified caller identity. The API journals no raw payer wallets, IP addresses, or signatures. `X402_EXPECTED_PAY_TO` pins the payment recipient to the official wallet by default. Tools advertise that auto-pay can spend money and repeated calls can incur another charge.

### Cursor / other local MCP clients

Use the same `mcpServers` configuration shown above. For Cursor, put it in `.cursor/mcp.json` in your project. Inspect mode needs no wallet. Set `X402_MAX_PER_CALL_USDC` before enabling auto-pay; repeated calls spend again. Keep wallet credentials in local environment settings, outside Git.

## Registry publication

The `Publish MCP Registry` GitHub workflow validates the matching npm version, then publishes `server.json` using GitHub OIDC. It runs on a published GitHub release or a manual dispatch from main. No npm token, GitHub PAT, or wallet key is stored in CI. Actions and official publisher source are pinned to verified commits. npm publication still happens separately before creating the release.