Tree Data Structure for Manager Employee Hierarchy

employee_hierarchy_tree.xml

<record id="employee_hierarchy_tree_view" model="ir.ui.view">
	<field name="name">hr.employee.hierarchy.tree</field>
	<field name="model">hr.employee</field>
	<field name="field_parent">child_ids</field>
	<field eval="20" name="priority"/>
	<field name="arch" type="xml">
		<tree string="Employees" toolbar="True">
			<field name="name"/>
			<field name="company_id"/>
			<field name="department_id"/>
			<field name="work_phone"/>
            		<field name="work_email"/>
			<field name="job_id"/>
			<field name="parent_id" invisible="1"/>
		</tree>
	</field>
</record>

<!--By using window action-->
<record id="window_action_employee_hierarchy_tree" model="ir.actions.act_window">
	<field name="name">Employee Hierarchy Window Action</field>
	<field name="type">ir.actions.act_window</field>
	<field name="res_model">hr.employee</field>
	<field name="domain">[('parent_id','=',False)]</field>
	<field name="view_type">tree</field>
	<field name="view_id" ref="employee_hierarchy_tree_view"/>
</record>

<menuitem name="Employee | Organization Hierarchy" id="menu_employee_hierarchy_for_window_action" action="window_action_employee_hierarchy_tree" sequence="1"/>

<!--By using server action-->
<record id="server_action_employee_hierarchy_tree" model="ir.actions.server">
	<field name="name">Employee Hierarchy Server Action</field>
	<field name="condition">True</field>
	<field name="type">ir.actions.server</field>
	<field name="model_id" ref="model_hr_employee" />
	<field name="state">code</field>
	<field name="code">action=self.load_employee_hierarchy(cr, uid, context.get('active_ids', []), context=context)</field>
</record>

<menuitem name="Employee | Organization Hierarchy" id="menu_employee_hierarchy_for_server_action" action="server_action_employee_hierarchy_tree" sequence="1"/>

is triggering an error when I try to create this view.

"Validation Error

Invalid view hr.employee.hierarchy.tree definition in False"
Tried on 16 and 17 CE.
When I remove toolbar="True", I can create a view,
I was not able to find "toolbar" in views architecture documentation.
Any hint?