Prioritize measurable KPIs: storage density (pallets/m2), throughput (orders/day), and SLA adherence. Verify WMS capability, APIs for marketplace/carrier integration, and real-time reporting. Map coverage by delivery zones and transit times, and confirm scalability for seasonal peaks and value-added services like kitting and returns handling.

Key drivers: space (per pallet or m2), handling (inbound/outbound moves), pick-and-pack rates, packaging/kitting fees, and carrier costs. Compare total cost-per-order under realistic SKU velocity scenarios, include cross-dock and storage minimums, and request lane-specific quotes that reflect last-mile cost variance in the region.

Look for inventory segmentation (DC vs. forward stock), reliable slotting and picking accuracy, multicarrier integrations, batch kitting, and reverse logistics processes. Also ensure 3PLs can handle mixed carton orders, offer SLA-backed dispatch windows, and provide visibility across channels for unified inventory management.

Request route-specific transit-time matrices and recent POD samples. Validate carrier partnerships for road, air, and intermodal lanes, run pilot shipments to measure real-world transit and variability, and confirm customs/clearance expertise for cross-border corridors to avoid delays during peak seasons.