@xenarch/agent-mcp

Non-custodial x402 MCP server for AI agents. Lets Claude, Cursor, LangChain and CrewAI pay for HTTP 402–gated APIs with USDC micropayments on Base L2. Unlike Cloudflare Pay-Per-Crawl, works on any host and settles agent-to-publisher direct.

Source

npm

Version: 0.2.2

Version published: 4 months ago

Maintainers: 2

Created: 5 months ago

Source

Xenarch — non-custodial x402 MCP server for AI agent payments

Xenarch is a non-custodial x402 MCP server that gives any AI agent a wallet and lets it resolve HTTP 402 ("Payment Required") responses automatically. When a site, API, or tool returns HTTP 402 with an x402 challenge, the agent signs a USDC micropayment on Base L2 (up to $1 per call) and retries — no API keys, no subscriptions, no credit card on file. The agent wallet only ever needs USDC — no ETH, no gas coin of any kind.

What makes Xenarch different

	Cloudflare Pay-Per-Crawl	TollBit	Xenarch
Works on any host	✗ (Cloudflare only)	✗ (enterprise)	✓
Non-custodial	✗	✗	✓ (agent-to-publisher direct, no Xenarch contract)
Agent needs ETH	n/a	n/a	✓ never
Fee	Platform rate	Platform rate	*0% — no Xenarch contract that can* charge a fee**
Open standard	proprietary	proprietary	x402 + pay.json (open)

Native in

Claude Code, Claude.ai (via MCP), Cursor, Cline, LangChain, CrewAI, and any MCP-compatible client.

Why x402

HTTP 402 has been reserved in the HTTP spec since 1997 for exactly this — machine-to-machine payment. x402 is the open protocol that finally uses it: a signed USDC micropayment any server can verify and any agent can produce.

Why pay.json

pay.json is the open standard for machine-readable pricing, served at /.well-known/pay.json. Think robots.txt for payments.

FAQ

How does Claude pay for APIs with Xenarch? Install the Xenarch MCP server, give it a wallet, and Claude resolves any HTTP 402 response automatically with a USDC micropayment on Base L2.

Is Xenarch custodial? No. Payments settle on-chain as a direct USDC transfer from the agent's wallet to the publisher's wallet. Funds never touch Xenarch infrastructure — there is no Xenarch contract in the money flow.

Does the agent need ETH for gas? No. USDC is the only token the agent wallet ever needs. Fund it with USDC and you're done.

What's the fee? 0%. There is no Xenarch contract that can charge a fee — the architecture is structurally zero-fee, not a policy promise.

What's the max payment? $1 per call.

Learn more: https://xenarch.com

Install

npm install @xenarch/agent-mcp

Add to Claude Code:

claude mcp add xenarch -- npx -y @xenarch/agent-mcp

Configure

Variable	Default	Description
`XENARCH_PRIVATE_KEY`	—	Wallet private key (overrides config file)
`XENARCH_RPC_URL`	`https://mainnet.base.org`	Base RPC endpoint
`XENARCH_API_BASE`	`https://xenarch.dev`	Xenarch platform API
`XENARCH_NETWORK`	`base`	Network (`base` or `base-sepolia`)
`XENARCH_MAX_PAYMENT_USD`	—	Max USD per call to auto-approve without prompting (defaults to 0.1 USDC inside x402-fetch)