"Alexa, inspect my cavity"
"What is the finesse of a cavity with transmissivities of 100 ppm and 20 ppm...
"What is the storage time of a cavity with a finesse of 2000"
This skill allows you to convert between various characteristics of your optical cavity: finesse, storage time (also called the photon decay time) and cavity pole. These quantities can additionally be derived from optic transmissivities.
For more information on these quantities, see Wikipedia: Fabry-Perot interferometer (Theory section).