Place garlic in a small saucepan; cover with water. Bring to a boil. Reduce heat; simmer 2 minutes. Drain; set garlic aside.
Sprinkle chicken with pepper. Heat oil in a large Dutch oven over medium-high heat. Add chicken; cook 10 minutes or until browned, turning once. Remove chicken from pan. Increase heat to high; add wine to pan. Cook until reduced to 1 cup (about 5 minutes). Remove from heat. Stir in garlic, drumsticks, thighs, broth, tomato, and tomato paste. Bring to a boil. Reduce heat; simmer 5 minutes. Add breast halves; cover and cook 20 minutes, turning chicken after 10 minutes. Remove chicken from pan; keep warm.
Increase heat to medium-high; add olives and capers to pan. Cook, uncovered, 10 minutes, stirring occasionally. Return chicken to pan, turning to coat. Cover and let stand 5 minutes. Serve with couscous. Garnish with parsley, if desired.