A medium-sized tool bag offers a versatile solution for storing and transporting a moderate range of tools. Key features to look for include durable materials like nylon or canvas, reinforced stitching, and strong zippers for longevity. Ensure the bag has multiple compartments and pockets for organization, along with sturdy handles and possibly shoulder straps for comfort. Consider water-resistant models for protection in wet environments. Research reputable brands like Bosch, and check reviews to find the best quality and fit for your needs.