Universal Crypto MCP

# x402 Payment Protocol for Universal Crypto MCP > **Give Claude Money!** 💰 AI agents can now pay for premium APIs automatically. ## What is x402? x402 implements the HTTP 402 Payment Required standard, enabling: - **Automatic payments**: AI agents pay for APIs without human intervention - **Micropayments**: Pay fractions of a cent per request - **USDs yield**: Payments use Sperax USDs stablecoin which earns ~5% APY ## Quick Start ### 1. Configure your wallet ```bash export X402_PRIVATE_KEY=0x... # Your EVM private key export X402_CHAIN=arbitrum # Default: arbitrum ``` ### 2. Fund your wallet Send USDs (Sperax USD) to your wallet address: - Get address: Use `x402_address` tool - Get USDs: Swap on [Uniswap](https://app.uniswap.org) or [SperaxDApp](https://app.sperax.io) ### 3. Make paid requests The AI agent can now use x402 tools to pay for premium APIs. ## Available Tools | Tool | Description | |------|-------------| | `x402_pay_request` | Make HTTP request with automatic 402 payment | | `x402_balance` | Check wallet balance (USDs + native) | | `x402_send` | Send direct payment to address | | `x402_estimate` | Check cost before paying | | `x402_networks` | List supported networks | | `x402_address` | Get your wallet address | | `x402_yield` | Check USDs yield earnings | ## Example Usage ### Pay for a premium API ``` User: "Get the premium weather forecast for Tokyo" Agent: [uses x402_pay_request to call weather API] [automatically pays $0.01 in USDs] [returns weather data] ``` ### Check balance ``` User: "How much do I have in my crypto wallet?" Agent: [uses x402_balance] "You have 45.23 USDs ($45.23) and 0.001 ETH" ``` ### Send payment ``` User: "Send $5 to 0x123..." Agent: [uses x402_send with amount="5.00"] "Sent 5.00 USDs. Transaction: 0xabc..." ``` ## Environment Variables | Variable | Description | Default | |----------|-------------|---------| | `X402_PRIVATE_KEY` | EVM private key (required for payments) | - | | `X402_CHAIN` | Default chain | `arbitrum` | | `X402_RPC_URL` | Custom RPC URL | Chain default | | `X402_MAX_PAYMENT` | Max payment per request | `1.00` | | `X402_ENABLE_GASLESS` | Enable gasless payments | `true` | | `X402_DEBUG` | Debug logging | `false` | ## Supported Networks | Chain | CAIP-2 | Testnet | |-------|--------|---------| | Arbitrum One | `eip155:42161` | No | | Arbitrum Sepolia | `eip155:421614` | Yes | | Base | `eip155:8453` | No | | Ethereum | `eip155:1` | No | | Polygon | `eip155:137` | No | | Optimism | `eip155:10` | No | | BNB Chain | `eip155:56` | No | ## Why USDs? [Sperax USDs](https://sperax.io) is a stablecoin that: - **Auto-rebases**: Your balance grows automatically (~5% APY) - **No claiming**: Yield appears in your wallet instantly - **Arbitrum native**: Low gas fees This means your AI agent's wallet balance **grows while it waits**! ## Security - Private keys are only read from environment variables - Never logged or exposed - Max payment limits prevent overspending - Testnet support for development ## Source Based on [x402-stablecoin](https://github.com/nirholas/x402-stablecoin) - Apache-2.0 license.