ax() API

Structured generation APIs for typed programs.

Most Used

Create an AxGen program from a string or parsed signature.

Rust

let qa = ax("question:string -> answer:string")?;

Structured generation program with indexed multi-sampling, winner selection, forward, streaming, optimization, trace, usage, and tool-call behavior.

Build a typed function tool. Rust uses tool because fn is reserved.

Field	Value
Kind	`function`
Ax concept	`fn`
API section	Tools
Form	`tool(name).description(...).arg(...).handler(...).build()`
Returns	ToolBuilder

Rust

let search = tool("search").description("Search docs").build();

Advanced / internals / full reference

Create a controller for scoped steering, reasoning updates, cancellation, and queued/applied lifecycle events. Pass it through forward options.

Rust

let control = run_control();

Run control shared by active and future descendant programs. Cancellation reports unresolved work and does not undo external effects.

Callable tool descriptor with JSON-schema-compatible parameters and a host handler.

Open the full Rust reference. This page highlights the ax symbols most relevant to everyday use.