Locked inside or missing altogether?
If the keys are visible inside, explain that and say where the vehicle is parked. If no key can be found, mention whether you have a spare elsewhere and whether the vehicle uses a conventional ignition or push-button start. A replacement-key request is not the same job as opening a locked vehicle.
Have the vehicle details ready
The make, model and year help assess the request. Also mention any remaining working key, the type of fob and whether the vehicle currently starts. Key cutting, electronic pairing and availability of suitable parts depend on the vehicle. Confirm the supported work and estimate before assuming that a particular make or model can be handled.
A Cambridge landmark is only a starting point
Being near Harvard Square or Alewife does not identify the car. Provide the street address or parking facility, the vehicle location and the entrance someone can use. For a garage, include the level and any restrictions the garage operator has communicated. Do not send account passwords or confidential access credentials as routine location details.
A spare key is a different conversation
If you still have a working key and want another, make that clear. It may change the information and steps needed to assess the job. If a fob has stopped working, explain whether its buttons, the door access or the starting function are affected. A failed function alone does not establish which part needs replacing.
Authorization and the estimate
Have information ready to establish your authority over the vehicle. Ask which charges apply to the visit, access work, key or fob, and any programming. If you cannot safely wait beside the vehicle, describe your location when arranging assistance. Stay clear of moving traffic while you make the call.