Your application

Tidewave is an example of a MCP server that runs inside your application. It currently is available for Phoenix and Rails. Phoenix installation:

# mix.exs
{:tidewave, "~> 0.1", only: :dev}

# lib/my_app_web/endpoint.ex
# just above the `if code_reloading? do` block
if Code.ensure_loaded?(Tidewave) do
  plug Tidewave
end

Rails installation:

gem "tidewave", group: :development

Example .cursor/mcp.json:

{
  "mcpServers": {
    "tidewave": {
      "url": "http://localhost:4000/tidewave/mcp"
    }
  }
}

For Claude and others, they recommend an mcp-proxy.