What is the right course of action now?

Your answer is correct because you should not overtake when the tractor intends to pull out to the left. According to German traffic rules, if a slow vehicle signals it wants to change lanes or pull out (in this case to the left), you must not overtake immediately since this could cause a dangerous situation. You should wait until the tractor has completed or canceled its maneuver and it is safe to pass. This rule ensures the safety of all road users by preventing conflicts during lane changes or turns. Therefore, even if the overtaking distance appears sufficient, you must respect the tractor’s indication and hold back until the situation is clear.