Eucalyptus essential oil can be useful for productivity and mental clarity. Its strong and refreshing aroma is known for its cooling and invigorating properties that can help improve focus, concentration, and energy levels. Eucalyptus oil is commonly used in aromatherapy to help clear the mind and enhance mental alertness, making it a useful oil for productivity. However, it's important to note that eucalyptus oil can be irritating to the skin and mucous membranes if not diluted properly, so it should be used with caution and avoided by people with certain medical conditions.