Agent for a model that can answer questions and call tools. Add another primitive when you can name the requirement it serves. They can be combined: a workflow can contain agents, and a harness can drive an Agent.
A support assistant, at different stages
An Agent is enough to answer a shipping question, search policies, and call your order API. The tutorial begins there. A Workflow helps when a return must follow fixed steps: validate the order, check eligibility, obtain approval, then invoke the payment service. The model may help classify the request; application code enforces the sequence. A Team helps when specialist behavior is the requirement: route a billing question to a billing agent or coordinate several analyses. Each member still needs scoped tools and a clear stopping condition. A Harness helps when several deployments share a support ability but have different grants, runtime drivers, context, or budgets. Its canonical history and the Agent’s backing storage have separate ownership. Durable execution helps when an approval or external operation may outlive the process. A queue alone can redeliver a job; the durable driver must decide whether to resume, skip, or reconcile an operation that may already have happened.Three decisions to make first
- Who chooses the next step? A model-led Agent, a host-defined Workflow, or a Team coordinator.
- How long does the work live? One connection, a background job, or a persisted task across restarts.
- Who may do what? Bind tools and resources to verified identity and host policy.