Prioritize measurable KPIs and systems compatibility: on-time-in-full (OTIF), inventory accuracy, dock-to-stock cycle time, and order lead time. Ensure the 3PL supports EDI/API integration, real-time inventory visibility, and configurable WMS workflows to align fulfillment with your order profiles and carrier routing rules.

Look for facilities with ample dock positions, mezzanine and racking flexibility, automated sortation or scan-verify pick systems, dedicated returns processing areas, and quality-inspection stations. These reduce touches per order, improve picking accuracy, and shorten resolution times for reverse logistics.

Closer proximity reduces linehaul costs and transit variability, enabling tighter SLAs and lower inventory buffer needs. It also expands carrier options for expedited lanes and reduces last-mile distance to dense consumer markets, which lowers parcel spend and improves delivery predictability.

Include clearly defined KPIs (OTIF, accuracy, lead time), transparent unit and accessorial rate tables, reconciliation cadence, and chargeback rules. Add clauses for capacity commitments, seasonal scalability, audit rights, and escalation paths tied to measurable service remedies to mitigate cost leakage and service degradation.