I know that, inevitably, the cooler the functionality of an extension, the more permissions it requires, but I get uncomfortable giving "read and change all you

I know that, inevitably, the cooler the functionality of an extension, the more permissions it requires, but I get uncomfortable giving "read and change all your data on all websites" and "modify data that you copy and paste" permissions to someone I don't know—even though I understand that those permissions are legitimate for the core functions of the extension! Could you give some information to help reassure me that I can trust this extension?