Search for the "Tags for Documentation Comments" topic in MSDN for all the available documentation tags.
Then in your project, go to the Project Properties dialog, to the Configuration Properties/Build tab and specify a file for the XML Documentation File property. This will generate a file by that name when you compile your assembly. Place this xml file beside your dll. This will provide Intellisense support for your types in that assembly.
To provide Description support for your properties in the property grid in the designer, add the DescriptionAttribute attribute to your properties in code.