FrontierAI.Engineer
Tool Use & Function Calling

API Tool

An API tool is a tool that wraps an external HTTP API, exposing one or more endpoints as callable functions within an agent's action space. The tool handles authentication, serialization, and error normalization so the agent can invoke real-world services — such as weather data, CRM systems, or payment processors — with typed arguments and reliable return values, without the model needing to know raw HTTP details.