Ax Signatures For Python

This skill helps an agent write Python code with the generated Ax package axllm. Use the generated package API, examples, and manifests; do not import TypeScript-only APIs unless you are editing the TypeScript package.

When To Use

• Declare input and output contracts with native generated-package APIs.
• Generate JSON-schema-compatible shapes for outputs, tools, prompts, and validation.
• Keep Standard Schema and TypeScript-only helper libraries out of generated-language code.

Package Facts

• Language: Python.
• Package: axllm.
• Package API docs: API.md and axir-api.json.
• Capability manifest: axir-capabilities.json.
• Runnable examples: examples/.
• Real network support: yes.
• Scripted no-key transport support: yes.
• Runtime profiles: javascript-quickjs, python-pyodide.

Core Pattern

from axllm import s

sig = s("question:string -> answer:string")
schema = sig.to_json_schema("outputs")

More Patterns

Simple string contract

Use the string form when field names and types are enough.

from axllm import ax

program = ax("questionText:string -> answerText:string")

Bounded class output

A class field constrains the model to a known label set.

router = ax(
    'messageText:string -> routeClass:class "support, sales, engineering"'
)

Fluent constraints

Python exposes the native fluent builder for validation constraints and objects.

from axllm import f

signature = (
    f()
    .input("contactEmail", f.string("Contact email").email())
    .output("partySize", f.number("Guests").min(1).max(12))
    .output("bookingCode", f.string().regex(r"^[A-Z]{3}-\d{4}$"))
    .build()
)

JSON schema

Render the output contract for tools, validators, or external consumers.

schema = signature.to_json_schema("outputs")

Reuse the signature

Pass one built signature into AxGen and call it like any other program.

program = ax(signature)
output = program.forward(client, inputs)

Start from the complete programs under examples/, then browse the larger gallery at https://axllm.dev/python/subsystems/s/.

Relevant API Surface

• Signatures: s, f, AxSignature
• Tools: fn, Tool

Guardrails

• Start from package examples for exact native syntax before inventing a new call shape.
• Use provider-api examples only when the user explicitly has provider credentials available.
• Use no-key examples for deterministic local checks and provider request mapping.
• Treat AxIR as the source of generated package truth: if package docs disagree with source code, update the compiler and regenerate packages.
• Do not copy repo-maintainer skills from tools/*/skills/ into user packages.