Build an MCP Server

=== list_tools ===
  get_order: Look up one ShopTiny order by id (item, amount_usd, status).
  list_orders: List all known ShopTiny order ids.
  get_refund_policy: Return the ShopTiny refund policy markdown text.

=== call_tool get_order(4412) ===
{
  "id": "4412",
  "item": "laptop stand",
  "amount_usd": 12,
  "status": "delivered"
}

=== call_tool get_refund_policy ===
{
  "text": "# ShopTiny refund policy\n- Orders under $100 may be auto-refunded for damaged items.\n- Orders $100 or more need human approval before refund.\n",
  "source": "data/refund_policy.md"
}