Using Extended Properties to limit the call to sp_msforeachtable

ListOfTables.sql

SELECT s.name [Schema], t.name [Table],
    CAST(Value AS nvarchar(500)) AS [MS_Description]
FROM sys.extended_properties AS ep
JOIN sys.tables t
    on ep.major_id = t.object_id
join sys.schemas s
    on s.schema_id = t.schema_id
WHERE ep.name = N'MS_Description' AND ep.minor_id = 0
    and LOWER(CAST(Value AS nvarchar(500))) like '%lookup%'
order by s.name, t.name

sp_msforeachtableAndExtProp.sql

USE AdventureWorks
GO

EXEC sp_msforeachtable @command1 = 'EXECUTE sp_spaceused [?];'
  ,@whereand = 'AND o.id in (
    SELECT ep.major_id 
      FROM sys.extended_properties AS ep 
      WHERE LOWER(CAST(Value AS nvarchar(500))) LIKE ''%lookup%'' 
          AND ep.name = N''MS_Description'' 
          AND ep.minor_id = 0)'