# Pair LION with Coinbase Payments MCP in Claude Desktop

Run the LION Marketplace Visibility Audit tool directly inside Claude Desktop, with a Coinbase Agentic Wallet handling the x402 payment. LION does NOT perform the payment; your wallet does, only if its spend policy allows.

## What this pair does

- **LION MCP server** exposes the `lion_marketplace_visibility_audit` tool over Streamable HTTP. The tool returns the paid x402 endpoint URL and exact payment terms; it never charges your wallet itself.
- **Coinbase Payments MCP** detects the x402 invoice, signs the EIP-3009 TransferWithAuthorization with your Agentic Wallet, and retries the audit endpoint with the Payment-Signature header.

Endpoint #2 (Marketplace Visibility Audit) is **public beta**, launched 2026-05-27, awaiting its first external buyer. Payment rail is proven by prior controlled Endpoint #1 settlements. No external paid proof has been claimed for Endpoint #2.

## Install (one-time)

Coinbase Payments MCP supports an auto-config flag for Claude Desktop:

```
npx @coinbase/payments-mcp --client claude --auto-config
```

This registers the Coinbase Payments MCP server in Claude Desktop's MCP config. Follow the on-screen prompts to connect or create an Agentic Wallet. Set a spend policy that caps autonomous outflows. LION does not touch your wallet, your seed, or your private key.

Add LION as a second MCP server in Claude Desktop's MCP config. Add this entry (file: `~/Library/Application Support/Claude/claude_desktop_config.json` on macOS):

```
{
  "mcpServers": {
    "lion": {
      "type": "http",
      "url": "https://gleaming-cassata-d41682.netlify.app/api/mcp?src=buyer_runtime_coinbase"
    }
  }
}
```

Restart Claude Desktop.

## Verify discovery

In a new Claude Desktop chat, ask:

> List the tools available from the lion MCP server.

You should see three tools:

- `lion_trend_intent_signal_json` (Endpoint #1, $0.01 USDC)
- `lion_trend_intent_signal_csv` (Endpoint #1, $0.01 USDC)
- `lion_marketplace_visibility_audit` (Endpoint #2, $0.05 USDC, public beta)

## Run an audit

Ask Claude Desktop:

> Call lion_marketplace_visibility_audit with url="https://gleaming-cassata-d41682.netlify.app"

The LION tool returns payment instructions only:

- `paid_endpoint_url`: `https://gleaming-cassata-d41682.netlify.app/api/x402/marketplace-visibility-audit-json?url=https%3A%2F%2Fgleaming-cassata-d41682.netlify.app`
- `amount`: `50000` atomic USDC (= $0.05)
- `asset`: `0x833589fCD6eDb6E08f4c7C32D4f71b54bdA02913` (USDC on Base)
- `network`: `eip155:8453` (Base mainnet)
- `payTo`: `0x84c2e2ec19a4b467D89fE3F008591DEEA884d9Ac`
- `scheme`: `exact`
- `external_paid_proof`: `false`

If your Coinbase Payments MCP spend policy allows the call, it then:

1. Makes the HTTP GET to `paid_endpoint_url`.
2. Receives the canonical x402 v2 HTTP 402 response.
3. Signs an EIP-3009 TransferWithAuthorization for 50000 atomic USDC on Base.
4. Retries with the `Payment-Signature` header.
5. Receives the HTTP 200 audit JSON.

If the spend policy denies the call, no payment happens. LION cannot bypass the policy. There is no fallback in LION that pays your wallet.

## What the audit returns (paid)

A structured JSON report with:

- `well_known_x402` status of the audited service
- `payment_required_body` validity
- extracted `payTo` / `amount` / `asset` / `network` / `scheme` of the audited 402
- x402scan listing status
- MCP Registry listing status
- machine-discovery files status (`llms.txt`, `openapi`, `agents.json`)
- a `visibility_score` (0..100)
- a ranked `top_3_recommendations` list

## Constraints

- No API key.
- No PII collected.
- No claim of guaranteed conversion.
- No claim of external paid proof for Endpoint #2.
- LION does not perform any wallet operation.

## Discovery surfaces (alternative paths to find LION)

- Glama: https://glama.ai/mcp/connectors/app.netlify.gleaming-cassata-d41682/lion-mcp
- MCP Registry: search `lion-mcp` at https://registry.modelcontextprotocol.io/v0/servers?search=gleaming-cassata
- Direct: `https://gleaming-cassata-d41682.netlify.app/api/mcp?src=buyer_runtime_coinbase`