x402engine-mcp

Agent-friendly MCP server for x402engine. It lets agents discover and call pay-per-request APIs through HTTP 402, with automatic USDC payment on Base or Solana.

The live gateway covers LLMs, image and video generation, web search and scraping, code execution, crypto and wallet data, transaction simulation, audio, travel, and IPFS. This MCP exposes a curated tool set and live discovery for the full catalog.

Quick Start

Use a dedicated, low-balance payer wallet. The MCP signs x402 payments locally and never sends the private key to x402engine.

Base

{
  "mcpServers": {
    "x402engine": {
      "command": "npx",
      "args": ["-y", "x402engine-mcp@1.1.0"],
      "env": {
        "X402_EVM_PRIVATE_KEY": "0xYOUR_DEDICATED_PAYER_KEY",
        "X402_PAYMENT_NETWORK": "base",
        "X402_MAX_PAYMENT_USD": "1.00"
      }
    }
  }
}

Fund the wallet with USDC on Base. The x402 facilitator pays transaction gas; the wallet signs an EIP-3009 USDC authorization.

Solana

{
  "mcpServers": {
    "x402engine": {
      "command": "npx",
      "args": ["-y", "x402engine-mcp@1.1.0"],
      "env": {
        "X402_SOLANA_PRIVATE_KEY": "YOUR_BASE58_OR_JSON_PRIVATE_KEY",
        "X402_PAYMENT_NETWORK": "solana",
        "X402_MAX_PAYMENT_USD": "1.00"
      }
    }
  }
}

Fund the wallet with USDC on Solana and enough SOL for transaction fees.

Discovery Without a Wallet

The server starts without a wallet, and free tools such as discover_services and service_health still work. Paid tools return their x402 payment requirements until a wallet is configured.

claude mcp add x402engine -- npx -y x402engine-mcp@1.1.0

Payment Controls

Variable	Default	Description
X402_EVM_PRIVATE_KEY	unset	Dedicated payer key for Base USDC
X402_SOLANA_PRIVATE_KEY	unset	Base58 or JSON payer key for Solana USDC
X402_PAYMENT_NETWORK	auto	auto, base, or solana
X402_MAX_PAYMENT_USD	1.00	Hard per-request spending limit
X402_BASE_URL	production gateway	Override the gateway URL
X402_PAYMENT_HEADER	unset	Legacy pre-signed x402 header
X402_DEV_BYPASS	unset	Development bypass secret

In auto mode, Base is preferred when both keys are configured. Automatic payment only accepts the canonical USDC contracts on Base and Solana. It rejects unknown assets, unsupported networks, and amounts above the configured cap before signing.

MegaETH remains available to clients that supply their own compatible payment header.

MCP Tools

Category	Tools
Discovery	discover_services, service_health
Image and code	generate_image, execute_code
Audio	transcribe_audio
Crypto	get_crypto_price, get_crypto_markets, get_crypto_history, get_trending_crypto, search_crypto, get_crypto_categories
Wallet and token	get_wallet_balances, get_wallet_transactions, get_wallet_pnl, get_token_prices, get_token_metadata
IPFS	pin_to_ipfs, get_from_ipfs
Travel	search_flights, search_locations, search_hotels, search_cheapest_dates

Prices are included in each tool description and in live discovery. The gateway catalog can change independently of this package.

Discovery

• Gateway discovery: /.well-known/x402.json
• Agent card: /.well-known/agent.json
• Endpoint manifest: /.well-known/agent-manifest.v1.json
• Services API: /api/services
• Package metadata: server.json

Development

npm install
npm test
npm run build

Links

• Website: x402engine.app
• npm: x402engine-mcp
• GitHub: agentc22/x402engine-mcp
• Protocol: x402.org