Cipher X402 MCP Server

cipher-x402-mcp

An MCP server that exposes 8 Solana / crypto / macro tools to any MCP-aware client (Claude Desktop, Cursor, Cline, Continue, etc.). Seven of the tools are gated behind the x402 payment protocol — agents auto-pay in USDC on Base, $0.005 – $0.25 per tool call. One tool is free (educational).

The server is a forward-only relay: when an agent calls a paid tool without an X-PAYMENT header, we surface the upstream HTTP 402 + accept-list verbatim so the agent's own wallet signs the payment. We never custody caller funds.

Tools

Payment recipient: 0xa0630fAD18C732e94D56d2D5F630963eb8fB9640 (Base, USDC 0x833589fCD6eDb6E08f4c7C32D4f71b54bdA02913).

Install (Claude Desktop)

Add this to ~/Library/Application Support/Claude/claude_desktop_config.json (macOS) or %APPDATA%\Claude\claude_desktop_config.json (Windows):

{
  "mcpServers": {
    "cipher-x402": {
      "command": "npx",
      "args": ["-y", "cipher-x402-mcp"]
    }
  }
}

Restart Claude Desktop. The 8 tools show up in the tool tray.

Install (Cursor / Cline / Continue)

Any MCP-over-stdio client works the same way — the launcher is npx -y cipher-x402-mcp.

Install (Smithery)

npx -y @smithery/cli install cipher-x402-mcp --client claude

Remote HTTP transport

Deployed at https://cipher-x402-mcp.vercel.app/mcp (streamable HTTP). Probe the manifest at the root URL.

How payment works

1. Agent calls (e.g.) solana_wallet_scan({ "address": "..." }) without a payment.
2. Server returns a structured result starting with HTTP 402 Payment Required — upstream returned an x402 accept-list. followed by the JSON accept-list (price, network, payTo, asset, etc.).
3. Agent's wallet signs an EIP-3009 authorization for the advertised maxAmountRequired.
4. Agent re-invokes the same tool with { "address": "...", "_payment": "<base64-signed-header>" }.
5. Server forwards the X-PAYMENT header upstream, upstream's facilitator verifies + settles on Base, and the content is returned to the agent.

The server itself is stateless — no API keys, no user session, no funds.

Develop locally

git clone https://github.com/cryptomotifs/cipher-x402-mcp
cd cipher-x402-mcp
npm install
npm run build
npm run smoke     # tool-registry smoke test
npm start         # stdio transport
npm run start:http  # HTTP transport on :8080

Deploy HTTP transport (Vercel)

vercel link
vercel --prod

The /mcp route serves MCP JSON-RPC messages; / serves a lightweight JSON manifest used by registries.

Environment overrides

All upstream base URLs are overridable (useful for private mirrors):

CIPHER_SCAN_API_URL=https://your-scan.example.com \
CIPHER_PWNED_URL=https://your-pwned.example.com \
  npx cipher-x402-mcp

Related

• cipher-starter — free MIT Solana solo-dev playbook (github.com/cryptomotifs/cipher-starter).
• cipher-solana-wallet-audit — free GitHub Action (v1.1.0) that fails CI on plaintext Solana private keys (github.com/cryptomotifs/cipher-solana-wallet-audit).
• cipher-x402 — four premium chapters, paid in USDC on Base at cipher-x402.vercel.app.

License

MIT — see LICENSE.