Currently the module suggests a meta description "less than 320 characters long":
Every page should have a unique Meta Description, ideally less than 320 characters long.
Actual recommendation (i.e. the amount of characters that actually get displayed in Google) is between 120 to 158 characters. Mobile results have less space (and show fewer characters), desktop results have more space (and bigger limit). Google did use the 300+ char limit for some months between 2017 and 2018, but that change was relatively short lived :)
Overall I think that suggesting "ideally less than 320 characters" is misleading for authors who may not be aware of existing limits. As such, I think that "ideally less than 160 characters" would be a good compromise.
Currently the module suggests a meta description "less than 320 characters long":
Actual recommendation (i.e. the amount of characters that actually get displayed in Google) is between 120 to 158 characters. Mobile results have less space (and show fewer characters), desktop results have more space (and bigger limit). Google did use the 300+ char limit for some months between 2017 and 2018, but that change was relatively short lived :)
Overall I think that suggesting "ideally less than 320 characters" is misleading for authors who may not be aware of existing limits. As such, I think that "ideally less than 160 characters" would be a good compromise.