ax-verification

ax-verification is a skill for Claude Code, Codex from shenli/devtool-ax-kit. It costs 15 tokens per session (191 once invoked), scanned A, original, Apache-2.0.

A method for creating independent checks that confirm whether an agent's software task actually works. The checks test observable behavior, such as saved data after a restart, rather than relying on the agent's own report.

In plain words
What is it for?
Use it to verify tool-based tasks, including persistence, duplicate actions, timing boundaries, malformed responses, and missing credentials.
Why use it?
It catches false success reports and prevents the agent from weakening the checks to hide a failure.

Skill for Claude CodeCodex

Install

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.

agentmods
npx agentmods add skills/shenli/devtool-ax-kit/ax-verification
Any agent
npx skills add shenli/devtool-ax-kit --skill ax-verification
Clone the repo
git clone --depth 1 https://github.com/shenli/devtool-ax-kit

Made for: Claude Code, Codex.

Wrote 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.

agentmods badge for ax-verification

README.md
[![agentmods](https://agentmods.dev/badge/skills/shenli/devtool-ax-kit/ax-verification.svg)](https://agentmods.dev/skills/shenli/devtool-ax-kit/ax-verification)
Your own site
<a href="https://agentmods.dev/skills/shenli/devtool-ax-kit/ax-verification"><img src="https://agentmods.dev/badge/skills/shenli/devtool-ax-kit/ax-verification.svg" alt="Measured on agentmods" height="20"></a>
Per session 15 Skills are progressive disclosure: only the name and description are preloaded; the body loads when the skill is used.
When invoked 191 The whole file, excluding the scripts and references it only reads on demand.
Security scan A 0 findings. Scan, not verified.
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 $0.00015 $0.00191
Opus 5 $0.00008 $0.00096
Sonnet 5 $0.00003 $0.00038
Haiku 4.5 $0.00002 $0.00019

Measured 3d ago against content hash ce0c783ff33b, method: parsed. Prices are Anthropic first-party input rates as of 2026-08-30, from the pricing page.

Security

Grade A, and why

ax-verification 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 3d 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.

skills/ax-verification/SKILL.md · 23 lines

What it actually says

Define assertions outside the agent's editable workspace. Verify observable behavior, not implementation shape: functional outputs, persistence across a restart, independent identities, effect counts, and credential absence where relevant. Return structured pass/fail results with details and a nonzero exit status on failure.

Run the verifier separately after the agent finishes. Do not let the agent edit the verifier or turn a missing assertion into a pass. Keep checks local or explicitly scoped to disposable test resources.

For timing-sensitive behavior, deliberately exercise the boundary and use a fresh identity per trial. Report valid-trial denominators separately from infrastructure availability.

Record disagreement between the agent's reported result and the independent result as a first-class outcome. Exercise timing, restart, duplicate-effect, and malformed-response boundaries when those are part of the task contract.

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. 3d ago First seen · 23 lines · 15 tokens per session scan A ce0c783ff33b

Subscribe to this mod's changes

ax-verification is a skill published in the GitHub repository shenli/devtool-ax-kit (2 stars, last pushed 4d ago), licensed Apache-2.0. It adds 15 tokens to every session and 191 once invoked, about $0.0001 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 2026-08-31.

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