A managed security service provider takes responsibility for an agreed set of security activities. The label alone does not tell you which systems are covered, who responds to an alert, or when support is available. Those details belong in the service agreement.
Start with responsibilities
List the security work your team needs help with. Ask each provider to explain what they will own, what remains with your team, and what depends on another vendor. Identify who can approve changes and how urgent issues will be escalated.
Ask what you will receive
Review sample reports, reporting frequency, and the information you can access during an engagement. Ask who will perform the work and what experience they have with environments similar to yours.
Review the terms
Check coverage hours, response targets, exclusions, access requirements, and how the arrangement ends. Distinguish an alert notification from a commitment to investigate or remediate it. Compare the written scope against your actual needs.