Usability
Interface 
User-friendliness/complexity of the tool´s interface
Straightforward, intuitive
Time efficiency Time needed for mastering the „how-to“ of the tool and a production of a task
High. It may take some time for a contribution (pronunciation) to be approved by the site, but as a learner, it is a great and quick way to accurately know how words are pronounced.
Interface language(s) The number of languages in which the tool is currently available/adaptable to
Interface available in 40+ languages; pronunciation for words in more than 300 languages available.
Respect for privacy Does the tool require registration? Who can see my data? Can I remain anonymous?
Medium/high. Forvo collects personal information such as username, email address, date of birth, gender, and spoken or studied language, together with service metadata, login information and others, for different operational and analytical purposes and to market its products. It does not sell data to third parties and shares it only to run the service. One of these third parties is Google Ad Manager and Google Analytics. Forvo’s privacy policy mentions the use of measures to ensure the security, secrecy, and confidentiality of data. Users are also informed about their rights to access, rectify, erase, restrict processing, object, and data portability. Forvo stores user data in the EEA, and processes it in compliance with applicable legislation, including Regulation (EU) 2016/677, that is the GDPR. See more here.
Saving work for future use Possiblity to save your or others´ work for reuse/reproduction
Yes. Users with a profile can bookmark and save words.
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)
Medium. Virtually any word can be found on Forvo.