You can truncate the description text like follows:
<asp:Label id="Label6" runat="server" text='<%# Eval("description") != null ? TruncateText(Eval("description").ToString(), 200) : string.Empty %>'></asp:Label>
TruncateText(Eval("description").ToString(), 200) displays first 200 characters of the description text.
public string TruncateText(string inputText, int length)
{
if (inputText.Length <= length)
return inputText;
var delimiters = new[] { ' ', '.', ',', ':', ';' };
var index = inputText.LastIndexOfAny(delimiters, length - 3);
if (index > (length / 2))
return inputText.Substring(0, index) + "...";
return inputText.Substring(0, length - 3) + "...";
}