Does the attack from a Mystic’s Bestial Claws take an action?

This question is about the UA Mystic (v3).

The Bestial Form Immortal Discipline has this possible effect:

Bestial Claws (1-7 psi). You manifest long claws for an instant and make a melee weapon attack against one creature within 5 feet of you. On a hit, this attack deals 1d10 slashing damage per psi point spent.”

The vast majority of Mystic effects specify that they take an action, a reaction, a bonus action or a given number of minutes, but this one doesn’t specify anything in that regard. Does it mean that “Bestial Claws” doesn’t use up an action ?

If so, this would mean that you may take the Attack action, and then do an additional attack with this effect. Furthermore, I didn’t see anything that prevents a Mystic from using several effects on the same turn, so would that mean that he can make as many “Bestial Claws” attacks as he wants (provided he has the psi points) in one turn ?