diff-skill

A comparison check for two versions of a skill's Markdown instructions.

In plain words
What is it for?
Use it when reviewing or comparing changes to a skill's instructions.
Why use it?
It focuses on finding regressions, such as lost guidance or unnecessary complexity, after an edit.

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/serpro69/claude-toolbox/diff-skill
Any agent
npx skills add serpro69/claude-toolbox --skill diff-skill
Clone the repo
git clone --depth 1 https://github.com/serpro69/claude-toolbox

Made for: Claude Code, Codex.

Per session 106 Skills are progressive disclosure: only the name and description are preloaded; the body loads when the skill is used.
When invoked 528 The whole file, excluding the scripts and references it only reads on demand.
Security scan A 0 findings. Scan, not verified.
Origin unknown 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 $0.00106 $0.00528
Opus 5 $0.00053 $0.00264
Sonnet 5 $0.00021 $0.00106
Haiku 4.5 $0.00011 $0.00053

Measured 2d ago against content hash cc43248b08b5, method: parsed. Prices are Anthropic first-party input rates as of 2026-08-30, from the pricing page.

Security

Grade A, and why

diff-skill 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 2d 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.

klaude-plugin/skills/diff-skill/SKILL.md · 45 lines

The source is not reproduced here

No licence file

A repository with no LICENSE is all rights reserved by default, so the body is not copied here. The metadata, the measurements and the link are.

Read it on GitHub

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. 2d ago First seen · 45 lines · 106 tokens per session scan A cc43248b08b5

Subscribe to this mod's changes

diff-skill is a skill published in the GitHub repository serpro69/claude-toolbox (148 stars, last pushed 2d ago), with no licence file. It adds 106 tokens to every session and 528 once invoked, about $0.0005 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 2026-08-30.

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