HTML5 error validation

Hi there.

I was wondering if HTML5 error validation with the generic error This fields is required' comes under Error suggestion 3.3.3? For example: we have text inputs with the labels 'First name (required) - 'Last name (required) for example...yes focus is taken straight to the first name....but the error is ambiguous for screen reader users and does not suggess what is required? Or it this more usability?

Thank you.