Below are the formal and polite equivalents (synonyms) of 'tell' which you can use in your business or professional pieces of writing:
It has exactly the same meaning and uses as 'tell'.
'If you can inform your staff about the new procedures, it will be very much appreciated.'
It has exactly the same meaning and uses as 'tell/inform'.
'If you can notify your staff about the new procedures, it will be very much appreciated.'
Although it has same meaning as 'tell/inform', when you use 'brief' it suggests that you did it for a long time and in a lot of detail.
'If you can brief your staff about the new procedures, it will be very much appreciated.'
It is a very formal way of saying 'tell/inform'. It should only be used when writing to very educated people.
'When we are aware of the new procedures, we will apprise you immediately.'