Ax Signatures For Python

Use when writing Python code with axllm for string signatures, field descriptors, JSON schema output, validation, and typed tool argument shapes.

Install

Install only this skill for Python:

Shell

npx skills add https://ax-llm.github.io/ax/python/ --skill 'ax-python-signature'

Published skill file: ax-python-signature/SKILL.md.

Source

Source: packages/python/skills/ax-python-signature/SKILL.md
Version: 23.0.5

Skill Instructions

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

Python

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.

Python

from axllm import ax

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

Bounded class output

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

Python

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

Fluent constraints

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

Python

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.

Python

schema = signature.to_json_schema("outputs")

Reuse the signature

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

Python

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.