Why OleDbSchemaGuid Not Support Description Field?

Why OleDbSchemaGuid Not Support Description Field? in this code return All field from database but Description of Columns and Tables are always = "" ! how can i get description from database ?

    Dim Schema = conn.GetOleDbSchemaTable(OleDbSchemaGuid.Columns, New Object() {Nothing, Nothing, Name, Nothing})
For i = 0 To Schema.Rows.Count - 1
   Dim culmSchema As New ColumnSchema
                    With culmSchema
                        .DatabaseName = Schema.Rows(i)!TABLE_CATALOG.ToString()
                        .Schema = Schema.Rows(i)!TABLE_SCHEMA.ToString()
                        .TableName = Schema.Rows(i)!TABLE_NAME.ToString()
                        .Name = Schema.Rows(i)!COLUMN_NAME.ToString()
                        .Description = Schema.Rows(i)!DESCRI开发者_如何转开发PTION.ToString() ' Return String.Empthy Always!! 
Next i 
End With

Thanks!