delta-skill

delta-skill is a skill for Claude Code, Codex from JustMichael-80/MasterVault. It costs 10 tokens per session (29 once invoked), scanned A, original, MIT.

A test fixture for checking whether a skill installer can discover an add-on. It is explicitly not a real skill.

In plain words
What is it for?
Use it in tests of skill installation and discovery workflows.
Why use it?
It helps test installer discovery without relying on a real add-on.

Skill for Claude CodeCodex

Written for no agent in particular: nothing here depends on one.

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/justmichael-80/mastervault/delta-skill
Any agent
npx skills add JustMichael-80/MasterVault --skill delta-skill
Clone the repo
git clone --depth 1 https://github.com/JustMichael-80/MasterVault

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 delta-skill

README.md
[![agentmods](https://agentmods.dev/badge/skills/justmichael-80/mastervault/delta-skill.svg)](https://agentmods.dev/skills/justmichael-80/mastervault/delta-skill)
Your own site
<a href="https://agentmods.dev/skills/justmichael-80/mastervault/delta-skill"><img src="https://agentmods.dev/badge/skills/justmichael-80/mastervault/delta-skill.svg" alt="Measured on agentmods" height="20"></a>
Per session 10 Skills are progressive disclosure: only the name and description are preloaded; the body loads when the skill is used.
When invoked 29 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 5.1 $0.00010 $0.00029
Opus 5 $0.00005 $0.00015
Sonnet 5 $0.00002 $0.00006
Haiku 4.5 $0.00001 $0.00003

Measured 6d ago against content hash b922c31d964c, method: parsed. Prices are Anthropic first-party input rates as of 2026-09-06, from the pricing page.

Security

Grade A, and why

delta-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 6d 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.

Origin

Copies of this mod

1 near-identical copy found in the catalogue:

tests/fixtures/curated-repo/delta-skill/SKILL.md · 6 lines

What it actually says

Fixture skill for installer discovery tests. Not a real skill.

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. 6d ago First seen · 6 lines · 10 tokens per session scan A b922c31d964c

Subscribe to this mod's changes

delta-skill is a skill published in the GitHub repository JustMichael-80/MasterVault (12 stars, last pushed 24d ago), licensed MIT. It adds 10 tokens to every session and 29 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 2026-08-30.

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