Summary

An agent reaches a dozen services without holding an account at any of them.

Each call carries its own price and settles in stablecoin, so there is no subscription to manage per vendor. The ceiling matters more than the convenience: the cap is checked before anything is signed, which is what makes handing a wallet to an agent a bounded decision.

What it is

A client for the x402engine gateway: pay-per-request APIs reached through HTTP 402, with payment signed locally in USDC on Base or Solana. The gateway's catalog spans LLMs, image and video generation, web search and scraping, code execution, crypto and wallet data, transaction simulation, audio, travel and IPFS; this package exposes a curated tool set plus live discovery of the rest.

What you get

Discovery that works before any wallet exists — what the gateway currently offers and whether it is healthy, free to call
Crypto market data: current prices, markets, historical series, what is trending, search, and the category breakdown
Wallet and token data for an address: balances, transaction history, profit and loss, token prices and token metadata
Image generation and sandboxed code execution
Audio transcription
IPFS content pinned and fetched back
Travel search across flights, locations, hotels and cheapest dates
Prices carried in each tool's own description and in live discovery, so what a call costs is visible before it is made
Payment refused before signing when it does not fit: unknown assets, unsupported networks and anything above your cap are rejected, and automatic payment accepts only the canonical USDC contracts on Base and Solana

Requirements

Node, run over stdio from npm as x402engine-mcp. Nothing else for discovery — the server starts without a wallet, and paid tools simply return their payment requirements until one is configured. To pay automatically, give it a dedicated low-balance payer key: X402_EVM_PRIVATE_KEY for Base, where the facilitator covers gas and the wallet signs an EIP-3009 USDC authorization, or X402_SOLANA_PRIVATE_KEY for Solana, which also needs a little SOL for fees. X402_PAYMENT_NETWORK chooses between them and prefers Base when both are set. X402_MAX_PAYMENT_USD is a hard per-request ceiling, 1.00 by default. The key is signed with locally and never sent to x402engine. X402_BASE_URL moves the gateway and X402_DEV_BYPASS skips payment while testing.

Setup effort

One command — npx -y x402engine-mcp@1.1.0