What does a managed agent runtime actually handle?
The unglamorous majority of agent engineering: isolated sandboxes per session, scheduling and event triggers, retry logic, state between steps, execution traces for audit, and the scaling under all of it. That is most of what an agent harness team would otherwise build and operate by hand. You keep the parts that encode your business: the task definition, the tool access, the approval rules and the budgets. The vendor keeps the plumbing running at 3 a.m.
Who sells managed agents?
Every major AI vendor shipped a version through 2026. Anthropic’s Claude Managed Agents added scheduled deployments of server-hosted sessions on AWS in October (Anthropic release notes, 14 October 2026, read 19 October 2026). Microsoft’s Foundry Agent Service runs containerized agents in per-session isolated sandboxes, AWS sells the same shape as Bedrock AgentCore, and Google deploys agents on Vertex AI’s managed runtime. The pitch is identical across vendors: agents as infrastructure you rent, priced by usage rather than by the engineers who would otherwise babysit them.
What do you give up by buying the runtime?
Control, portability and sometimes compliance fit. The execution environment is the vendor’s, so its regions, data handling and limits become yours, and an agent built against one runtime’s primitives moves to another as a migration project. A managed runtime is the fastest way to production and the slowest way back out, which makes it a classic build or buy decision: the cost is not the subscription, it is the exit. Ask where sessions execute, what is logged and retained, and whether traces can be exported to your own observability stack.
When are managed agents the right call?
When the agent matters more than the infrastructure. A mid-sized company automating a back-office workflow gets to production in weeks on a managed runtime, with isolation and tracing it would struggle to build well, and the full agent lifecycle from pilot to retirement handled in one place. Run it like any background agent: explicit budgets, scoped tool access, and a human gate on consequential actions. Build your own runtime only when agents are your product or your compliance regime forces it.