Prioritize measurable KPIs: order cycle time, pick-and-pack accuracy, OTIF delivery, inventory accuracy, and returns processing time. Also require visibility (real-time WMS access), service-level credits for missed SLAs, and documented exceptions handling to align 3PL performance with customer expectations.

Port proximity and local carrier density reduce transshipment and last-mile legs, cutting transit time and variability. Consolidation opportunities and regular feeder schedules help lower per-unit ocean and LTL costs, while multiple parcel partners enable tiered delivery speeds for omnichannel promises.

Look for WMS with multi-node inventory visibility, SKU-level cycle counting, RF scanning, parcel carrier integration, and returns management workflows. Automation for high-velocity SKUs, configurable batching, and APIs for order orchestration are critical for consistent omnichannel performance.

Model fixed costs (rack/slot fees, minimums), variable handling (pick/pack, kitting), inbound receiving and put-away, storage by cube/time, outbound parcel and freight, customs duties and bonded warehouse fees, and value-added services. Include projected SKU velocity to calculate true cost-to-serve.

Request documentation of bonded warehouse status, customs brokerage partners, and past audit records. Verify EDI/API connectivity for declarations, review duty deferral options, confirm procedural SOPs for inspections, and ask for references demonstrating compliant cross-border handling.