I employed a carer's agency to provide three times a day visit to my Mother and we had a diary arrangement where every visit had notes such as what Mum had to eat, whether she had a shower, was distressed or anything else which was necessary information for the next person coming in, and for me to read as well. They used it to ask me for shopping items and to communicate in general and it was extremely useful. I wouldn't be happy with your carer taking notes about your Mother off the premises, these notes are confidential, if informal, and unless every visit is made by the same person, communication must be difficult. Remember you are the customer here, paying for a service, and must insist, within reason, how you wish the service to be provided. This is a business transaction, however kind the carer, and it is not a favour.