Mayor Walter E. Washington will speak at a breakfast meeting Tuesday of the Washington Board of Realtors at the Capital Hilton. Washington's two major opponents for the Democration nomination for mayor of the District, Sterling Tucker and Marion Barry, spoke recently to a WBR convention at sethe Homestead. Washington was unable to accept the invitation at that time.

Horowitz-Seigel designed the small, contemporary office building that developers Stanley Halle and William MacQuilliam have completed at Washington Boulevard and Annapolis Road in Seabrook, Md. The two-story, brick building is completely leased.

The written realty exams for brokers and sales agents in the District will be held at 8:30 a.m. Tuesday at Harambee House, 2225 Georgia Ave., NW.

Neighborhood Housing Services Inc., with funding from the District, has opened a tool-lending library at 1314 V St. SE. Hours are 5:30 to 6:30 p.m. Tuesday, Wednesday and Thursday and 10 to 11:30 a.m. Saturday. The facility will provide tools at no charge to city residents who want to work on their homes.

Nyman Realty Inc. has set up a new office in a remodeled, traditional building in Waldorf to serve the Southern Maryland area. Nyman, an affiliate of the Gallery of Homes since 1972, has six other offices in this area.

The Retired Officers Association Inc., now in leased space in downtown Washington, will move in October into a building the TROA bought recently at 201 N. Washington St., Alexandria. The Braedon firm is managing the four-story building.

Developer John D. Ringle, who has subdivided and sold hundreds of five-acre lots in the Dominion Valley area of south-central Fairfax County over the past decade, has opened the last of 10 communities.

Carriage House Associates Inc. has opened a fourth office at 5803 Rolling Rd. in the Springfield-Burke area of Virginia. Peter J. O'Brien is the manager.

Sunrise Associates, a building firm headed by Leonard Booth and Dominick Magarill, has opened a group of 26 houses in the Fairway Woods section of Reston. Booth, who has been in building for 35 years, formerly was with the Minchew and Yeonas firms. Magarelli, whose building experience spans 18 years, formerly was with the Yeonas and Levitt firms. The four-bedroom houses being built by the Sunrise firm are on 17,000-square-foot lots.