Hello delgertsetseg,

Put button in the tree view and apply attrs on it.

You have to also add state field in the tree view because attrs on state field so you can invisible it.

For Ex:-

<tree>

     <field name="state" invisible="1"/>

    <button name="add_workers" type="object" string="Add Workers" attrs="{'invisible' : [('state', '!=', 'draft')]}" confirm="Are You sure you want to Add Workers"/>

</tree>

Hope it will works for you.

Thanks,