Preheat oven to 350 F. Chop grapefruit.
Place baguette slices on baking sheet and toast 5-7 minutes, or until golden brown.
Rub toasted sides of bread with cut sides of garlic cloves; reserve.
In medium bowl, combine tomatoes, grapefruit, avocado, red onion, cilantro and olive oil; season with salt and pepper, to taste. Toss gently to combine.
Spoon grapefruit mixture over prepared bruschetta.
Garnish with fresh grapefruit segments and cilantro, if desired.