Designing and Building Agentic Systems: A 2026 Survey of the State of the Practice
The hard part of building an agentic system has moved out of the model and into the system around it. This survey distills 118 authoritative sources, gathered and independently verified through 9 July 2026, into a single account of how practitioners and researchers actually design agents today: when to build one at all, how to engineer context, tools, memory, and retrieval, how to reason and plan across long horizons, when multi-agent architectures help versus hurt, how to make long-running agents reliable and durable, how to evaluate and secure them, and what separates deployments that ship from the 95 percent of pilots that do not. Every claim carries an inline citation to a source whose quoted wording was confirmed verbatim on the live page. The recurring finding is that context, architecture, and organization, not raw model intelligence, are the binding constraints.