Many restaurants require their service employees to pool their tips. That is permissible. However, an employer cannot require any amount of the tip pool to be shared with non-service employees (for instance, managers who do not directly provide food service).
To learn more about tip pooling claims, read our blog post on a recent decision by the New York Court of Appeals (New York's highest court) setting out the standards for which employees can and cannot be included in a tip pool.