Hi rakeshkuma,

Apply jQuery tooltip.

Refer below code.

HTML

<asp:ScriptManager ID="ScriptManager1" runat="server">
</asp:ScriptManager>
<cc1:TabContainer ID="TabContainer1" runat="server" ActiveTabIndex="0">
    <cc1:TabPanel ID="TabPanel1" runat="server" HeaderText="TabPanel1" CssClass="toolTip" ToolTip="Tooltip_TabPanel1">
        <ContentTemplate>
            Tab 1
        </ContentTemplate>
    </cc1:TabPanel>
    <cc1:TabPanel ID="TabPanel2" runat="server" HeaderText="TabPanel2" CssClass="toolTip" ToolTip="Tooltip_TabPanel2">
        <ContentTemplate>
            Tab 2
        </ContentTemplate>
    </cc1:TabPanel>
    <cc1:TabPanel ID="TabPanel3" runat="server" HeaderText="TabPanel3" CssClass="toolTip" ToolTip="Tooltip_TabPanel3">
        <ContentTemplate>
            Tab 3
        </ContentTemplate>
    </cc1:TabPanel>
</cc1:TabContainer>
<script type="text/javascript" src="http://ajax.googleapis.com/ajax/libs/jquery/1/jquery.min.js"></script>
<link rel="stylesheet" href="https://code.jquery.com/ui/1.13.1/themes/base/jquery-ui.css" />
<script type="text/javascript" src="https://code.jquery.com/ui/1.13.1/jquery-ui.js"></script>
<script type="text/javascript">
$(function () {
    $(".ajax__tab_tab").eq(0).attr("title", "Tab Panel  1 ToolTip");
    $(".ajax__tab_tab").eq(1).attr("title", "Tab Panel  2 ToolTip");
    $(".ajax__tab_tab").eq(2).attr("title", "Tab Panel  3 ToolTip");
    $(".ajax__tab_tab").hover(function () {
        $(this).tooltip();
    });
})
</script>

Screenshot