First the answer, use the keyboard shortcut CTRL-SHIFT-SPACE, this should trigger the parameter info tooltip for you.
Secondly there is a problem here, since the tooltip should appear automatically. I have just typed the following simple test using VS2005 and VA 1626. When I accepted the function name "append" the caret was placed between the brackets and the parameter info tooltip appeared automatically.
static void testGeneralCode()
{
std::string strName;
strName.append(|)
}
Which IDE and version of VA are you using?
It is possible you have turned off an option to automatically show these tooltips.
