In an Agent plan, which statement best distinguishes a tool from an action?

• A. A tool is a concrete capability.
• B. An action is a specific input parameter to a tool.
• C. A tool is an abstract goal of the plan.
• D. An action is a system state change.

Answer: (A)

Tools are concrete capabilities the agent can call during planning and execution (for example, performing a web search, calling a calculator, or fetching data from an API). They represent tangible abilities provided by the environment that the agent can leverage to accomplish tasks. An action is the step the agent takes in its plan—the decision to perform something, which may involve invoking a tool or carrying out an internal operation. Labeling a tool as a concrete capability captures the sense that it’s the observable resource the agent can use. Saying an action is a specific input parameter to a tool would misframe actions as mere data passed to tools; the action is the step itself, not just one parameter. A tool isn’t an abstract goal of the plan, since goals are what you’re trying to achieve, while tools are the means to get there. And an action isn’t necessarily just a system state change; it’s the planned step the agent executes, which may include invoking tools, making decisions, or other operations, not only changing state.