Visual Studio - Summary Tag Comments - Optional Params

No, you can't. The only attribute being recognized by VS is the name, like that:

<param name="FileName" >The filename of the file to be loaded.</param>

The only thing that you can do - is to set xsl transform for your output document. But this won't have any effect on Intellisense.

You should provide an overload that omits the optional parameter:

/// <summary>/// Sets data associated with the instance using the default media type./// </summary>/// <param name="key">The key defining the data.</param>/// <param name="value">The data.</param>public void SetData(object key, object value){    SetData(key, value, null);}/// <summary>/// Sets data associated with the instance using the specified media type./// </summary>/// <param name="key">The key defining the data.</param>/// <param name="value">The data.</param>/// <param name="mime">The media type of the data.</param>public void SetData(object key, object value, string mime){    ...}

Alternatively, you can declare the parameter as optional:

/// <summary>/// Sets data associated with the instance./// </summary>/// <param name="key">The key defining the data.</param>/// <param name="value">The data.</param>/// <param name="mime">The media type of the data.</param>public void SetData(object key, object value, string mime = null){    ...}

You can use <remarks></remarks> tag. Doesn't exist special tag for optional params.