Usability
Interface 
User-friendliness/complexity of the tool´s interface
Intuitive, easy to navigate.
Time efficiency Time needed for mastering the „how-to“ of the tool and a production of a task
Medium; it is slightly more complex than other communication platforms since it has more functionalities, so it requires some time to get familiarised with the tool.
Interface language(s) The number of languages in which the tool is currently available/adaptable to
English and 27 other languages.
Respect for privacy Does the tool require registration? Who can see my data? Can I remain anonymous?
Medium. Discord collects various types of user data, including account information (e.g., username, email), content users create (e.g., messages, files), payment information, and information from users' actions on the platform. It does so to provide services, ensure safety, enforce community guidelines, offer customer support, and improve its services. Importantly, it emphasises not selling personal information to third parties, although it might share anonymised or aggregated data. Discord uses encryption to protect user data both in transit and at rest, which is a standard security measure. It also mentions access controls and two-factor authentication for added security. Discord provides users with various controls to manage their privacy, such as limiting and modifying data collection and deleting or disabling their accounts. Discord mentions compliance with various data protection frameworks, such as the GDPR. See more here.
Saving work for future use Possiblity to save your or others´ work for reuse/reproduction
Yes, with an account.
Tailorability (If so, how?) Possibility of the tool to be used for a range of different activities (e.g. to what extent you can organize a project assignment with a central activity based on this tool)
High; it can be used for many different purposes, plus users can create their own servers or find servers suited to their needs among hundreds.