An agent framework is a software library offering common components for building an agent system. It typically provides the execution loop, wiring for external capabilities, and state management, handling the basic orchestration of these elements. What it does not provide are the specific constraints, verification logic, or audit trails, which are distinct, system-specific elements of the harness. Frameworks evolve quickly; the long-term integrity and reliability of an agent system reside in its bespoke harness.
Frameworks accelerate initial development by abstracting away boilerplate, allowing quick iteration on core agent logic. However, this convenience often leads to a misattribution of system capabilities, where the framework is perceived as delivering a complete agent. In practice, a framework only provides the scaffolding; relying on it for crucial operational aspects like precise constraints or verification risks building systems that are brittle, uninterpretable, and prone to unpredictable failures when faced with actual operational demands.
The common misconception is to conflate the agent framework with the complete harness, or to expect the framework itself to supply system-level guarantees. While a framework helps with the mechanics of tool use and basic orchestration, it remains a generic utility. The critical work of defining explicit constraints, establishing robust verification steps for model outputs, and maintaining an auditable execution trail is specific to the application and must be implemented within the custom harness, not delegated to the framework.