A good AMC defines outcomes, scope and response expectations rather than simply promising availability.
Scope
List network devices, firewalls, controllers, critical services and exclusions.
Preventive work
Include configuration backup, health checks, firmware review where appropriate and documentation updates.
Reporting
Define incident records, recurring issues, recommendations and periodic review meetings where useful.
This article is general technical guidance. Actual architecture should be validated against the organization's requirements, risk profile and existing infrastructure.