When using comment based help, the system autogenerates parameter information from the parameters specified in the param statement.  However, it does not give the default value if one is specified.  For example, take the following snippet.
---------------------
<#
 .SYNOPSIS
Test

 .DESCRIPTION
Test
 
.PARAMETER Overwrite
 If present, specifies to overwrite the file

 .PARAMETER InputFile
 Specifies the path for the folder and file used for Input

 .PARAMETER OutputFile
 Specifies the path for the folder and file used for Output

#>

param(
    [switch] $overwrite=$false,
    [String] $Inputfile="C:\Foo.txt",
    [String] $OutputFile="C:\Bar.txt"
    )
---------------------------


If you use get-help -full on this code you get

---------------------------
PARAMETERS
    -overwrite []
        If present, specifies to overwrite the file

        Required?                    false
        Position?                    named
        Default value
        Accept pipeline input?       false
        Accept wildcard characters?

    -Inputfile
        Specifies the path for the folder and file used for Input

        Required?                    false
        Position?                    1
        Default value
        Accept pipeline input?       false
        Accept wildcard characters?

    -OutputFile
        Specifies the path for the folder and file used for Output

        Required?                    false
        Position?                    2
        Default value
        Accept pipeline input?       false
        Accept wildcard characters?
---------------------------


Why no default value?  How do you get the help to show the default value?