Mayor Walter J. Sullivan has summoned the Cambridge City Council to a special session next Monday night. Usually the council suspends action during the summer.

The man chosen in a nation-wide search to become Cambridge City Manager, James L. Sullivan, will probably appear in his official capacity for the first time at Monday's meeting. Sullivan took office at a council session last June 27, ending a six-month talent hunt for a new Manager.

Mayor Sullivan cited the following reasons for calling the meeting:

* To receive communications from the city manager.

* To receive communications from the mayor.

* To receive reports from Committees.

* To present petitions, orders, resolutions, and remonstrances.

* To receive communications and reports from city officers.

* To draw jurors.

* To consider any business that might interest the council.

The council may possible consider some "unfinished business" on its agenda, including a proposed amendment to the local zoning laws that would permit the construction of Cambridge Plaza, a high-rise office and apartment complex near the site of the future Kennedy Memorial Library.

I.M. Pei, architect for the Library, has opposed the zoning changes until a master plan for the Harvard Square area can be devised, and because he says that a 35-foot high garage on the complex site "would be a sort of blight" on one side of the Library.