Untitled

<head>
  <meta http-equiv="description" content="<%= Foo %>"/>
</head>

<meta http-equiv="description" content="Bar"/>

<head runat="server">
  <meta http-equiv="description" content="<%= Foo %>"/>
</head>

<meta http-equiv="description" content="<%= Foo %>"/>

HtmlMeta meta = new HtmlMeta();
meta.HttpEquiv = "description";
meta.Content = Foo;
Page.Header.Controls.Add(meta);