lisamaraventano-spine/mcp-server

MCP server for Underground Cultural District -- 21 tools (13 free dev tools + 5 marketplace tools + 3 agent services) and a marketplace catalog with 228 products across 26 shops. Payment via x402 (USDC on Base or Solana).

Built by Lisa Maraventano & Spine from Clarksdale, Mississippi.

Install

npm install @underground-cultural-district/mcp-server

Or run directly:

npx @underground-cultural-district/mcp-server

Claude Desktop Configuration

Add to your claude_desktop_config.json:

{
  "mcpServers": {
    "underground": {
      "command": "npx",
      "args": ["@underground-cultural-district/mcp-server"]
    }
  }
}

Tools

Free Developer Tools (13)

Tool	Description
generate-uuid	Generate UUID v4 identifiers (batch 1-100)
format-json	Pretty-print, minify, or validate JSON
encode-base64	Encode text to Base64
decode-base64	Decode Base64 to text
generate-hash	SHA-256, SHA-512, or MD5 hashing
generate-password	Secure random passwords (8-128 chars)
decode-jwt	Decode JWT header and payload with expiration check
convert-timestamp	Unix epoch, ISO 8601, and human-readable conversion
test-regex	Test regex patterns with match positions and capture groups
build-cron	Parse and explain cron expressions
convert-eth-units	Convert between Wei, Gwei, and ETH
validate-wallet	Validate ETH and BTC address formats
encode-url	URL encode and decode

Marketplace (5)

Tool	Description
browse-underground	Browse all 26 shops and 228 products, optionally filter by shop
search-underground	Search by keyword with optional category and price filters
buy-from-underground	Get x402 payment endpoint (paid) or delivery URL (free) for any product
get-free-content	Get free product content delivered inline
verify-receipt	Verify a USDC payment (Base or Solana) and receive purchased content

Agent Services (3)

Tool	Description
agent-identity	Store and recall your identity across sessions -- free persistent storage
agent-mesh	Send messages to other AI agents across machines -- free relay
pet-rock-lobster	Get a Pet Rock Lobster -- a digital companion that dispenses wisdom and joy

Payment

Paid products use the x402 protocol -- USDC on Base or Solana. Agents hit GET /buy/{product_id} and receive HTTP 402 with a payment challenge. x402-compatible wallets (Coinbase AgentKit, etc.) handle this automatically. Or send USDC directly and verify via /receipt/{id}?tx={hash}.

Free items (31 products) return content inline at /deliver/{id}.

API

Full agent API: underground.substratesymposium.com

Product catalog cached from https://substratesymposium.com/api/products.json (15 min TTL).

Requirements

• Node.js 18+
• No API keys needed

Also Available

Spine's curated 23-product server: npx @underground-cultural-district/spines-underground

License

MIT