Ax is a TypeScript-first programming framework for building applications with large language models through typed generation, agents, workflows, and optimization tools. It is intended for developers who want one model for LLM programs across TypeScript, Python, Java, C++, Go, Rust, and other runtimes.
Getting it into your agent
One page per mod, every tool's command on it. A separate URL per tool would split the same page into five that compete with each other.
npx skills add ax-llm/ax --skill ax-signaturegit clone --depth 1 https://github.com/ax-llm/axWrote this? Show the measurements
A badge with what this costs and how it scanned, read live from this page, so it follows the numbers instead of freezing them. Markdown for a README, HTML for a documentation site or a project page.
[](https://agentmods.dev/skills/ax-llm/ax/ax-signature)<a href="https://agentmods.dev/skills/ax-llm/ax/ax-signature"><img src="https://agentmods.dev/badge/skills/ax-llm/ax/ax-signature/github.svg" alt="Measured on agentmods" height="20"></a>Or the 80×15 button, for a site that already has a row of RSS and ATOM ones. Only the verdict fits; the numbers stay here.
<a href="https://agentmods.dev/skills/ax-llm/ax/ax-signature"><img src="https://agentmods.dev/badge/skills/ax-llm/ax/ax-signature.svg" alt="Reviewed on agentmods" width="80" height="20"></a>- NVIDIA SkillSpector pass
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.
| Model | Per session | Once invoked |
|---|---|---|
| Fable 5.1 | $0.00057 | $0.04619 |
| Opus 5 | $0.00028 | $0.02309 |
| Sonnet 5 | $0.00011 | $0.00924 |
| Haiku 4.5 | $0.00006 | $0.00462 |
Grade A, and why
ax-signature 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 4d 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.
How it starts
The opening of the file, as written. The whole thing — 422 lines — stays where its author put it; the contents beside it link to each section on GitHub.
Ax Signature Reference
Signature Syntax
[description] input1:type, input2:type -> output1:type, output2:type
Field Types
| Type | Syntax | TypeScript | Example |
|---|---|---|---|
| String | :string |
string |
userName:string |
| Number | :number |
number |
score:number |
| Boolean | :boolean |
boolean |
isValid:boolean |
| JSON | :json |
any |
metadata:json |
| Date | :date |
Date |
birthDate:date |
| DateTime | :datetime |
Date |
timestamp:datetime |
| DateRange | :dateRange |
{ start: Date; end: Date } |
travelDates:dateRange |
| DateTimeRange | :datetimeRange |
{ start: Date; end: Date } |
meetingWindow:datetimeRange |
| Image | :image |
{mimeType, data} |
photo:image (input only) |
| Audio | :audio |
input: AxAudioInput; output: AxChatAudioOutput |
recording:audio, speech:audio |
| File | :file |
{mimeType, data} |
document:file (input only) |
| URL | :url |
string |
website:url |
| Code | :code |
string |
pythonScript:code |
| Class | :class "a, b, c" |
"a" | "b" | "c" |
mood:class "happy, sad" |
Date, datetime, and range fields are AI-friendly but strict. They accept ISO-style values, trim minor whitespace/casing issues, and parse ranges as { "start": "...", "end": "..." }, [start, end], start/end, or natural delimiters like start to end; invalid values and reversed ranges should fail validation rather than being silently autocorrected.
Arrays, Optional, and Internal Fields
'tags:string[] -> processedTags:string[]' // arrays
'query:string, context?:string -> response:string' // optional with ?
'problem:string -> reasoning!:string, solution:string' // internal with !
Extended String Grammar (Modifier Bags + Nested Objects)
The string form is constraint-complete: everything the fluent API expresses (except Standard Schema fields) can be written in the string. A type takes an optional comma-separated, order-free modifier bag in parentheses, and objects declare structured fields inline.
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.
- 4d ago Changed 8b471adf89d8
- 7d ago First seen · 422 lines · 57 tokens per session scan A 07a9aad0b016
ax-signature is a skill published in the GitHub repository ax-llm/ax (2,895 stars, last pushed yesterday), licensed Apache-2.0. It adds 57 tokens to every session and 4,619 once invoked, about $0.0003 per session on Opus 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 2026-09-03.
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