diff --git a/addons/hr/models/hr_plan.py b/addons/hr/models/hr_plan.py
index fb999597398..8f8288ebd95 100644
--- a/addons/hr/models/hr_plan.py
+++ b/addons/hr/models/hr_plan.py
@@ -5,9 +5,10 @@ from odoo import api, fields, models, _
 from odoo.exceptions import UserError
 
 
-class PlanActivityType(models.Model):
+class HrPlanActivityType(models.Model):
     _name = 'hr.plan.activity.type'
     _description = 'Plan activity type'
+    _rec_name = 'summary'
 
     activity_type_id = fields.Many2one(
         'mail.activity.type', 'Activity Type',
@@ -19,31 +20,39 @@ class PlanActivityType(models.Model):
         ('coach', 'Coach'),
         ('manager', 'Manager'),
         ('employee', 'Employee'),
-        ('other', 'Other')], default='employee', string='Responsible')
-    responsible_id = fields.Many2one('res.users', 'Responsible Person')
+        ('other', 'Other')], default='employee', string='Responsible', required=True)
+    responsible_id = fields.Many2one('res.users', 'Responsible Person', help='Specific responsible of activity if not linked to the employee.')
 
     @api.onchange('activity_type_id')
     def _onchange_activity_type_id(self):
         if self.activity_type_id and self.activity_type_id.summary and not self.summary:
             self.summary = self.activity_type_id.summary
 
-    def get_responsible_id(self, employee_id):
+    def get_responsible_id(self, employee):
         if self.responsible == 'coach':
-            self.responsible_id = employee_id.coach_id.user_id
-            if not self.responsible_id:
-                raise UserError(_('No user linked to the coach of %s. Please contact an administrator.') % employee_id.name)
+            if not employee.coach_id:
+                raise UserError(_('Coach of employee %s is not set.') % employee.name)
+            responsible = employee.coach_id.user_id
+            if not responsible:
+                raise UserError(_('User of coach of employee %s is not set.') % employee.name)
         elif self.responsible == 'manager':
-            self.responsible_id = employee_id.parent_id.user_id
-            if not self.responsible_id:
-                raise UserError(_('No user linked to the manager of %s. Please contact an administrator.') % employee_id.name)
+            if not employee.parent_id:
+                raise UserError(_('Manager of employee %s is not set.') % employee.name)
+            responsible = employee.parent_id.user_id
+            if not responsible:
+                raise UserError(_('User of manager of employee %s is not set.') % employee.name)
         elif self.responsible == 'employee':
-            self.responsible_id = employee_id.user_id
-            if not self.responsible_id:
-                raise UserError(_('No user linked to the employee %s. Please contact an administrator.') % employee_id.name)
-        return self.responsible_id
+            responsible = employee.user_id
+            if not responsible:
+                raise UserError(_('User linked to employee %s is required.') % employee.name)
+        elif self.responsible == 'other':
+            responsible = self.responsible_id
+            if not responsible:
+                raise UserError(_('No specific user given on activity.') % employee.name)
+        return responsible
 
 
-class Plan(models.Model):
+class HrPlan(models.Model):
     _name = 'hr.plan'
     _description = 'plan'