//! # Custom Agent Tool Implementation
//!
//! This example demonstrates how to create a custom tool using the `#[toolbox]` and `#[tool()]` macros
//! provided by the `agentai` crate. It sets up an AI agent with a custom tool that can fetch content
//! from a given URL, showcasing how to define and use your own tools with the `agentai` crate.
//!
//! To run this example from the terminal, enter:
//! ```bash
//! cargo run --example tools_custom
//! ```
//!
//! ## Source Code
//!
//! ```rust
//! ```