Ever since taking office Jan. 2, Mayor Marion Barry has emphasized his desire to set a new tone for the operation of city government. Apparently the mayor's lieutenants have picket up the hint and are trying to acxample, Jose Gutierrez replaced George R. Harrod as head of the D.C. Office of Personnel following Harrod's indictment by a grand jury. Harrod was alleged to have assaulted a woman personnel office employe when she tried to break off a sexual relationship with him.

One of the first things acting director Gutierrez did when he moved into Harrod's office last week was to order the sofa moved out. "It was important symbolically," a smiling Gutierrez told an acquaintance.

About a year ago, the D.C. City Council spent nearly $1 million to redesign the first and ground floors of the District Building as new offices for council members and their staffs.

The new council headquarters, with the fabric-covered walls, low-backed sofas and modern-looking-though soiled-chairs in the hallway are roomier, more convenient and more attractive than the previous council offices on the fifth floor.

But the mice who drew shrieks and curses from many council members and their aids in the upstairs quarters apparently have cousins below.

Just last week, a green-shirted building custodian came to retrieve one of the little critters who had been killed in a trap in the offices of the council's committee on transportation and environmental affairs. One aide noted it was the second mouse kill in as many days.

"There's a little hole in the wall behind the radiator," another aide remarked. "I think they're living in the chairman's office," which is next door to the committee.

When the head of B'nai B'rith International appeared before the council's finance and revenue committee to oppose a proposed lifting of that organization's congressinally bestowed property tax exemption, he was accompanied to the witness table by former corporation counsel John R. Risher Jr.

Risher, who served as chief city lawyer and mayoral confidante extraordinaire during Walter E. Washington's administration, is not registered as a lobbyist because, he insists, he is not lobbying, buy merely providing legal services to a client. Since leaving city government, Risher has returned to his old job with the firm of Arent, Fox, Kintner, Plotkin and Kahn.

"I don't do any lobbying at all," Risher explained later. Although he might be expected to be well in demand as a former chief city lawyer who helped shape much of the legislation now affecting the city and its citizens, Risher said he does not plan to peddle his past experience in the way. "I never intend to be a specialist in District of Columbia affairs," he said.

Two city hall ex's who did hope to capitalize on their past experience in the District Building were disappointed last week when the National Capital Planning Commission chose Reginald W. Griffith as its executive director.

Among the unsuccessful job seekers were Ben W. Gilbert, former director of the Metropolitan Planning Office in the Washington administration, and Rodney Coleman, who was Sterling Tucker's righ-hand man during Tucker's four-year tenure as City Council chairman.

Coleman, now a development consultant for the Pennyslvania Avenue Development Corporation, said he wanted the NCPC job badly.

"It gives one the opportunity to put together the urban scene as it's going to be developed," he said. "You have a strong hand in saying what the District of Columbia is going to look like and what it is going to be."

Coleman said he is still looking for a way to get involved with the development business that is booming in this city.

Gilbert, former deputy manager editor of The Washington Post and longtime conficante of ex-mayor Washington, was high on Mayor Barry's list of allegedly incompetent administrators and was quickly removed after Barry took office.

Having missed out on the NCPC job, Gilbert is now planning to set up his own consulting firm to work in a variety of areas. His specialty, he said, will be how decisions are made, "not only in planning and zoning, but also the media aspects."

"I do know something about something," Gilbert said.