AWS has outlined a pragmatic modernization pattern called agentic overlays. These are thin wrappers that let traditional REST services participate in agent-to-agent interactions and expose existing APIs as tools compatible with the Model Context Protocol.
The appeal is that enterprises can add agent capabilities without rebuilding core systems, duplicating business logic, or running parallel infrastructure. That reduces the risk of agent sprawl while keeping existing services in use.
For companies with large legacy estates, overlays may be a more realistic path to agent adoption than wholesale replacement.