aithy: Skill for Claude Code

.claude/skills/ax-gen/SKILL.md

ax-gen is a skill for Claude Code from dosco/aithy. It costs 86 tokens per session (5,138 once invoked), scanned A, original, Apache-2.0.

A set of instructions for generating TypeScript code with the @ax-llm/ax library, which connects programs to language models and structures their inputs and outputs.

In plain words
What is it for?
It is for creating and reviewing AxGen programs that generate structured results, validate them, stream partial results, retry failed outputs, or select and improve generated answers.
Why use it?
It helps avoid incorrect use of the library's generators, streaming, validation, assertions, and multi-step behavior. This reduces guesswork when writing AxGen code.

Skill for Claude Code

Written for Claude Code: installed under .claude/.

This is dosco/aithy's own configuration. It tells Claude Code how to work on aithy itself, so it is not a mod to install elsewhere. Copy it as a starting point and replace the rules that are about this project. Everything aithy configures →

Reuse

Borrowing it

Nothing to install: this file belongs to dosco/aithy. Take a copy, put it at the same path in your own repository, and replace the rules that are about this project with yours.

Copy the file
curl -O https://raw.githubusercontent.com/dosco/aithy/main/.claude/skills/ax-gen/SKILL.md
Clone the repo
git clone --depth 1 https://github.com/dosco/aithy

Made for: Claude Code.

Wrote this? Show the measurements

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README.md
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Per session 86 Skills are progressive disclosure: only the name and description are preloaded; the body loads when the skill is used.
When invoked 5,138 The whole file, excluding the scripts and references it only reads on demand.
Security scan A 0 findings. A grade says what 26 rules found in the file — not that it is safe. Third-party audits
  • NVIDIA SkillSpector pass 7 Sept 2026
How audits are shown
Origin original No closer match found in the catalogue.
Token cost

What it costs to keep this loaded

Counted locally with the o200k_base tokenizer, which is exact for GPT models; Claude uses its own tokenizer and its counts differ. Treat this as one consistent yardstick across the catalogue rather than a bill. Prices are per million input tokens.

ModelPer sessionOnce invoked
Fable 5.1 $0.00086 $0.05138
Opus 5.5 $0.00034 $0.02055
Sonnet 5.5 $0.00017 $0.01028
Haiku 4.5 $0.00009 $0.00514

Measured 1mo ago against content hash b1dfd2fbbcb2, method: parsed. Prices are Anthropic first-party input rates as of 2026-10-07, from the pricing page.

Security

Grade A, and why

ax-gen scanned grade A with 0 findings against 26 rules in 11 categories — prompt injection, anti-refusal, data exfiltration, privilege escalation, supply chain, agent snooping, system-prompt leakage, SSRF and excessive agency — measured 1mo ago.

A static scan of the body, not an audit. Every finding is printed with the line that produced it so you can judge whether it matters here. A mod is markdown that instructs an agent; that is exactly why what it instructs is worth reading.

Nothing flagged

None of the 26 patterns this scan looks for appear in this file: no shell pipes, no recursive deletes, no credential paths, no hidden text, no instruction-override or anti-refusal phrasing, no agent-config snooping. That is not a guarantee, it is the absence of the things that are checkable.

.claude/skills/ax-gen/SKILL.md · 564 lines

How it starts

The opening of the file, as written. The whole thing — 564 lines — stays where its author put it; the contents beside it link to each section on GitHub.

AxGen Codegen Rules (@ax-llm/ax)

Use this skill to generate AxGen code. Prefer short, modern, copyable patterns. Do not write tutorial prose unless the user explicitly asks for explanation.

Use the ax-mcp skill when AxGen attaches native MCP clients or consumes MCP prompts, resources, tools, tasks, subscriptions, authentication, or events.

Use These Defaults

  • Use ax(...) factory, not new AxGen(...).
  • Always pass an AI instance from ai(...) as the first argument to forward().
  • Streaming uses streamingForward(), not forward() with a stream option.
  • Use schema validation for field shape and constraints.
  • Use addAssert(...) for whole-output hard invariants with correction retries.
  • Use addStreamingAssert(...) for partial streaming hard invariants with fail-fast per-attempt correction retries.
  • Use bestOfN(...) / refine(...) for reward-scored complete outputs.
  • Step hook mutations are applied at the next step boundary (pending pattern).
  • stopFunction accepts a string or string[] for multiple stop functions.
  • Multi-step continues until: all outputs filled, stop function called, or maxSteps reached.

Canonical Pattern

import { ai, ax, s } from '@ax-llm/ax';

const llm = ai({
  name: 'openai',
  apiKey: process.env.OPENAI_APIKEY!,
});

// Inline signature
const gen = ax('input:string -> output:string, reasoning:string');

// Reusable signature
const sig = s('question:string, context:string[] -> answer:string');
const gen2 = ax(sig);

// With options
const gen3 = ax('input -> output', {
  description: 'A helpful assistant',
  maxRetries: 3,
  maxSteps: 10,
  temperature: 0.7,
});

const result = await gen.forward(llm, { input: 'Hello world' });
console.log(result.output);

Signatures from zod / valibot / arktype

ax() accepts any signature built with f(), and f().input() / .output() accept Standard Schema v1 validators directly — per-field or a whole z.object({...}):

Read the full file on GitHub · 564 lines

Changes

What this file has done since we first saw it

Hashed on every crawl. A supply-chain change to an agent config is a question of when, not whether, so the history is kept rather than the latest state alone.

  1. 1mo ago Changed · +68 lines · +24 tokens per session b1dfd2fbbcb2
  2. 1mo ago First seen · 496 lines · 62 tokens per session scan A 960b12da750a

Subscribe to this mod's changes

ax-gen is a skill published in the GitHub repository dosco/aithy (108 stars, last pushed 1mo ago), licensed Apache-2.0. It adds 86 tokens to every session and 5,138 once invoked, about $0.0003 per session on Opus 5.5. A static security scan graded it A with 0 findings. No closer match exists in the catalogue, so it is treated as the original; first seen 2026-08-30.