In the HF Agent framework, what is a Tool?

• A. A database query string.
• B. A callable capability (function or API) wrapped with metadata that the agent can invoke to perform a concrete task.
• C. A user instruction for the agent to ignore tools.
• D. A log entry for auditing.

Answer: (B)

Tools are callable capabilities—functions or API wrappers—that come with metadata describing what they do, how to call them, and what they return. This metadata lets the agent know which tool to use, what inputs are needed, and how to handle the output. The agent can then invoke the tool to perform a concrete task, such as querying a service or fetching data, and use the result to continue reasoning and respond. For example, a weather tool might be defined with a name, description, and a function that takes a city and units and returns current weather data; the agent would call this tool with the right arguments rather than fabricating data. This makes the description of a Tool precise: it’s an encapsulated, callable capability with a defined interface. A raw database query string, a user instruction to ignore tools, or a log entry doesn’t capture that callable, metadata-backed interface the agent can invoke to perform actions.