extra-skill

extra-skill is a skill for Claude Code, Codex from coolight7/agentxx. It costs 24 tokens per session (91 once invoked), scanned A, original, MIT.

A small demonstration skill added while the example-resources plugin loads. It confirms that runtime-registered skills can be seen and explains how this one was registered.

In plain words
What is it for?
Use it to verify runtime skill registration and understand the difference between code-registered skills and manifest-declared skills.
Why use it?
It helps test whether plugin code can contribute a skill during loading, even when the skill is not listed in the plugin's configuration file.

Skill for Claude CodeCodex

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

Good fit Use it to verify runtime skill registration and understand the difference between code-registered skills and manifest-declared skills.

Compare 6 skills from other repositories ↓
Install with agentmods
npx agentmods add skills/coolight7/agentxx/extra_skill
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.

Any agent
npx skills add coolight7/agentxx --skill extra_skill
Clone the repo
git clone --depth 1 https://github.com/coolight7/agentxx

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 extra-skill

README.md
[![agentmods](https://agentmods.dev/badge/skills/coolight7/agentxx/extra_skill/github.svg)](https://agentmods.dev/skills/coolight7/agentxx/extra_skill)
Your own site
<a href="https://agentmods.dev/skills/coolight7/agentxx/extra_skill"><img src="https://agentmods.dev/badge/skills/coolight7/agentxx/extra_skill/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.

agentmods 80×15 button for extra-skill

Your own site · 80×15
<a href="https://agentmods.dev/skills/coolight7/agentxx/extra_skill"><img src="https://agentmods.dev/badge/skills/coolight7/agentxx/extra_skill.svg" alt="Reviewed on agentmods" width="80" height="20"></a>
Per session 24 Skills are progressive disclosure: only the name and description are preloaded; the body loads when the skill is used.
When invoked 91 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.
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 $0.00024 $0.00091
Opus 5.5 $0.00010 $0.00036
Sonnet 5.5 $0.00005 $0.00018
Haiku 4.5 $0.00002 $0.00009

Measured 1mo ago against content hash 3076b8dd0f3c, method: parsed. Prices are Anthropic first-party input rates as of 2026-10-07, from the pricing page.

Security

Grade A, and why

extra-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 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.

agent/plugins/example_resources/skills_runtime/extra_skill/SKILL.md · 15 lines

What it actually says

Extra Skill

A demo skill contributed by the example_resources plugin at runtime (vtable register_skill_dir, not the declarative manifest section).

Workflow:

  1. Confirm you can see this skill.
  2. Explain that it was registered by plugin code during load, not by plugin.yaml.
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 First seen · 15 lines · 24 tokens per session scan A 3076b8dd0f3c

Subscribe to this mod's changes

extra-skill is a skill published in the GitHub repository coolight7/agentxx (6 stars, last pushed yesterday), licensed MIT. It adds 24 tokens to every session and 91 once invoked, about $0.0001 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 2026-08-31.

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