I recently build some smart controls for my residence. Alexa understands the words "Alexa, tell the device to run" about 2/3 of the time, which is infuriating. The other third of the time you end up with "Announcing, 'tell the device to run.'" Put any white noise in the background, a fan blowing, a tea kettle boiling, anything at all, and recognition drops to below 50%. But google isn't any better.