Usability
Interface 
User-friendliness/complexity of the tool´s interface
Easy to use.
Time efficiency Time needed for mastering the „how-to“ of the tool and a production of a task
Medium.
Interface language(s) The number of languages in which the tool is currently available/adaptable to
English.
Respect for privacy Does the tool require registration? Who can see my data? Can I remain anonymous?
High. VoiceThread collects two types of information: information voluntarily provided by users (such as name, email address, telephone number, password, and profile photo when creating an account) and information collected automatically, which includes the frequency and duration of user visits, device-specific information, log information, and location information, but only when users explicitly opt-in. However, this data is collected with the sole purpose of optimising the service. VoiceThread does not sell or rent user information to third parties for advertising or marketing purposes. Aggregated and non-identifying information may be shared publicly. Regarding security, VoiceThread employs administrative, technical, and physical safeguards to protect user information, as well as encryption technologies to secure data transmission. It acknowledges users’ rights to update, delete, or access their personal information through their account settings. Voicethread complies with the GDPR. See more here.
Saving work for future use Possiblity to save your or others´ work for reuse/reproduction
Yes; users can save work in their profile.
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)
To some extent; VoiceThread can be used to discuss different videos and is suitable for different learning environments.