The normal $300, $500 or $1000, or whatever you may have selected as your comprehensive coverage deductible, does not apply to a glass loss. You will be covered for the full amount of the loss without a deductible unless you opted for a $100 deductible for glass breakage when you started your comprehensive coverage.
Chapter 175: Section 113O of the General Laws of Massachusetts is where this information is listed. The MA DOI states that for more information regarding insurance questions to contact the Attorney General's Insurance line at 1-888-830-6277.
The Massachusetts Division of Insurance Standards for The Repair of Damaged Motor Vehicles (211 CMR 133.00) also speaks of glass breakage. Here it states that damage to motor vehicle glass shall be repaired rather than replaced if:
(a) damage to the windshield is outside the critical viewing area, which is that area covered by the sweep of the wipers originally provided by the vehicle manufacturer, exclusive of the outer two inches within the perimeter of that sweep.
(b) damage to the glass is minor, including, but not limited to, a crack less than six inches in length and stone breaks or bruises, bullseyes and star breaks less than one inch in diameter; and
(c) the repair will not impair the operational safety of the motor vehicle.
Insurers shall use reasonable efforts to ensure that, before any decision is made to replace glass, the damage is inspected to determine whether it is suitable for repair.