Unit 3 · Build a reliable AI-powered feature

Let the model call your code safely

You wrap a host capability with a name, purpose, typed arguments, result, and handler. The model sees when and how to call it while your app keeps control of execution.

fn()8 focused minutesNot started

Worked example

See the idea in context

use axllm::{tool, FieldType};

let search = tool("search")
  .description("Search docs")
  .arg("query", FieldType::string())
  .handler(|args| Ok(json!(["hit"])));

Explain when to call it
The name and description orient the model toward product documentation searches.
Constrain the call
query must be a string and the result is declared as a string.
Bind trusted code
searchDocs runs in your host environment when the tool is selected.

Run itIn your own project

cargo add axllm

use axllm::{ai, ax};
use serde_json::json;

let llm = ai("openai", json!({"apiKey": std::env::var("OPENAI_API_KEY")?}))?;
let classify = ax("review:string -> sentiment:class \"positive, negative, neutral\"")?;

Set OPENAI_APIKEY in your environment before running provider-backed code.

In the ax repo

From a clone of the ax repo:

npm run example -- rust src/examples/rust/generation/basic_generation.rs

Active practice

Show that you can use it

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Keep exploring

See the idea in context

Show that you can use it

Source-backed follow-up