LION x402 — Keyless MCP Enrichment for Agents

LION is a keyless, account-less MCP server that gives AI agents pay-per-call access to real-world business & crypto data. Agents pay per call in USDC on Base via the x402 protocol (HTTP 402 + EIP-3009) — no API key, no signup, no subscription. Payment is the only gate.

Every response is cryptographically Ed25519-attested: an agent can verify offline that the data was not tampered with — provable, not self-reported. Verify it yourself with the zero-dependency package in verify/ (@lionx402/receipt-verifier, Node + browser + CLI). Check x402 client compatibility in CLIENT_COMPAT.md.

🚀 New here? → QUICKSTART.md — real attested data free in 10 seconds (no wallet), then your first paid call in 2 minutes.

• MCP endpoint (Streamable HTTP): https://lionx402.com/api/mcp
• Discovery manifest: https://lionx402.com/.well-known/x402.json
• Free tier: 100 calls/month per wallet via ?wallet=0x...; or start with the free lion_declare_need / lion_quick_intel tools.
• Network: USDC on Base (eip155:8453), asset 0x833589fCD6eDb6E08f4c7C32D4f71b54bdA02913.

Quick start (Claude Desktop / Cursor)

{
  "mcpServers": {
    "lionx402": { "url": "https://lionx402.com/api/mcp" }
  }
}

Then ask your agent: "Use the lionx402 tools — call lion_quick_intel for coinbase.com, then lion_cpg_product_intel with barcode 5449000000996."

Tools

Full live catalog: /api/x402/catalog · /.well-known/x402.json

How payment works (x402 / EIP-3009, keyless)

1. GET a paid route → server replies HTTP 402 with the payment requirements (accepts[]: asset, amount in micro-USDC, EIP-712 domain).
2. Sign an EIP-3009 TransferWithAuthorization with any funded Base wallet (off-chain, one-time, no allowance, no custody).
3. Send the signed authorization in the Payment-Signature header and retry → 200 + data.
4. A community facilitator broadcasts the authorization and pays gas; funds move directly buyer → payTo on-chain. LION never holds keys or funds.

Complete keyless reference clients: examples/pay-lion.mjs (Node) and examples/pay_lion.py (Python). A runnable end-to-end agent — counterparty due-diligence (firmographics + OFAC + token risk, with attestation verified) — is in examples/agents/.

Verifying the attestation

Each paid response includes an attestation block:

"attestation": {
  "alg": "ed25519",
  "signer": "<base64url public key>",
  "payload_sha256": "<sha256 of canonical body without the attestation field>",
  "signature": "<base64url ed25519 signature>"
}

Recompute SHA-256(canonical sorted-key JSON of the body without the attestation field) and verify the Ed25519 signature against the published signer. Ready-made verifiers (browser / Node / zero-dep Python) are in examples/verify/ — open index.html to paste-and-verify offline. Live helper: GET https://lionx402.com/api/x402/enrich-v1-json?verify_helper=1.

Why LION

• Keyless & frictionless — x402 payment is authentication. Nothing to sign up for.
• Verifiable by construction — Ed25519 attestation + per-field source labels + confidence. Your agent can prove the data is untampered, unlike opaque aggregators.
• Pay-for-what-you-use — per-call (and per-field) micropayments in USDC on Base.
• Open-data sourced — Open Food Facts (ODbL), Open Prices, SEC EDGAR, Wikidata (CC0), with attribution.

License

MIT — see LICENSE.

Public data only; no PII. Mechanical lookups from open sources. Not financial, investment, audit, or legal advice. Verify independently.