Keryx MCP server — add Keryx to any agent

Give any MCP-capable agent (Claude Code, Claude Desktop, Cursor, …) a tool that asks Keryx a question. Keryx autonomously buys paid sources under a budget, answers with inline citations, and pays every creator it cites in USDC on Arc. The toll for each call is paid from your own Arc-testnet wallet — so every call is a real on-chain payment, visible live on keryx.cc/dashboard.

Tools

| Tool | What it does | |------|--------------| | ask_keryx | Ask a research question (+ optional USDC budget). Returns a cited answer and the creators Keryx paid downstream. Costs 0.02 USDC per call, paid from your wallet. | | keryx_wallet_status | Show the wallet this server pays from — address, balances, whether it's ready, and how to fund it. Run this first. |

Setup (≈3 minutes)

Published to npm as keryx-mcp — no clone, no build.

Add it to Claude Code (one line)

claude mcp add keryx -- npx -y keryx-mcp@latest

Or add it to any MCP client (Claude Desktop, Cursor, Windsurf, …)

{
  "mcpServers": {
    "keryx": {
      "command": "npx",
      "args": ["-y", "keryx-mcp@latest"]
    }
  }
}

Fund the wallet, then ask

1. Call keryx_wallet_status — it prints the wallet address it pays from.
2. Open the Circle faucet, pick Arc Testnet, paste that address. (20 USDC / 2h — also covers gas.)
3. Call ask_keryx with your question. The server deposits to Circle Gateway on the first call and pays the toll; Keryx researches, answers with citations, and pays the creators it cited.

That's it — the answer comes back with the on-chain payment proof and a link to the live dashboard where your call now appears as external traction.

Configuration (env)

All optional — sane Arc-testnet defaults are built in.

| Var | Default | Purpose | |-----|---------|---------| | KERYX_BASE_URL | https://keryx.cc | Keryx deployment to call. | | KERYX_BUYER_PRIVATE_KEY | (generated) | Bring your own funded Arc wallet instead of the generated one. | | KERYX_WALLET_FILE | ~/.keryx/buyer-wallet.json | Where the generated wallet is persisted. | | KERYX_GATEWAY_DEPOSIT | 0.5 | USDC moved into Gateway per top-up. | | KERYX_RPC_URL | https://rpc.testnet.arc.network | Arc testnet RPC. |

Real money, testnet. Calls settle real USDC on Arc testnet. The generated wallet holds only what you faucet into it; Keryx never touches your keys. To go mainnet, point KERYX_BASE_URL at a mainnet deployment and fund with real USDC — only with eyes open.

From source (development)

git clone https://github.com/tang-vu/keryx && cd keryx && npm install
claude mcp add keryx -- node --import tsx --no-warnings "$(pwd)/mcp/keryx-mcp-server.mts"

npm run build (in mcp/) bundles keryx-mcp-server.mts → dist/keryx-mcp.mjs with esbuild; that single file is what ships to npm and runs under plain node.