Parking your car around the Square will soon be a little easier.

Cambridge City Manager James L. Sullivan told the City Council last night that the Massachusetts Bay Transportation Authority had agreed to let the City use part of the MBTA's Bennett St. yards--the future site of the Kennedy Library--for a 130 car public parking lot.

Under a previous agreement with the MBTA, the City had used the lot for parking until about a year ago, when the MBTA--saying it needed the lot to rearrange its operations in the yards-- discontinued the parking agreement.

But the MBTA never made the operations changes, Sullivan said last night, commenting that it took "a long series of communications and correspondences" with the authority to reinstitute the agreement.

The area, which is entered from Bennett St, "should be available very soon"-- perhaps within a week--for parking use, Sullivan said. The poles of the parking meters once used there are still in place; only the meter heads need to be installed, he said.

The newly regained parking lot, however, will probably soon be lost again, since the MBTA must vacate the yards by January 1, 1970 to make way for the Kennedy Library construction. The title of the yards formally passed to the United States Government last spring, but the General Services Administration, the federal landlord, said in a letter that it had no objection to a City parking lot there until the MBTA pulled out.