is that creating a JS class under the hood or is just a hint for the compiler?
What I do , but I don't work with recent PHP versions is to create this as a class, then to make this easy to construct objects from JSON i add a static function fromObject or fromJson that does it for me. Using real classes could prevent bugs when working with shit APIs like Microsoft TTS , where they have 2 endponts and one returns objects like voice: {name:"Bob"} and the other voice: {Name:"Bob"} so my code will wrap both type of responses into a well defined class.
I don't think there is a PHPDoc annotation just to hint what that object looks like but I will be happey to be shown a way.