What is fanfande-plugin-structure?

A package-structure guide for Anybox and Fanfande-derived plugins. A plugin is an add-on package that can include skills, connectors, scripts, documentation, assets, or web files.

Use it to create, explain, review, or validate plugin folders, manifests, bundled skills, plugin services, sidebar views, and connector requirements.

It helps developers use the current manifest location and package layout instead of relying on older plugin formats.

How fanfan-de/anybox configures Codex

Reuse

Borrowing it

Nothing to install: this file belongs to fanfan-de/anybox. Take a copy, put it at the same path in your own repository, and replace the rules that are about this project with yours.

Copy the file

curl -O https://raw.githubusercontent.com/fanfan-de/anybox/master/.agents/skills/fanfande-plugin-structure/SKILL.md

Clone the repo

git clone --depth 1 https://github.com/fanfan-de/anybox

Made for: 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.

README.md

[![agentmods](https://agentmods.dev/badge/skills/fanfan-de/anybox/fanfande-plugin-structure/github.svg)](https://agentmods.dev/skills/fanfan-de/anybox/fanfande-plugin-structure)

Your own site

<a href="https://agentmods.dev/skills/fanfan-de/anybox/fanfande-plugin-structure"><img src="https://agentmods.dev/badge/skills/fanfan-de/anybox/fanfande-plugin-structure/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.

Your own site · 80×15

<a href="https://agentmods.dev/skills/fanfan-de/anybox/fanfande-plugin-structure"><img src="https://agentmods.dev/badge/skills/fanfan-de/anybox/fanfande-plugin-structure.svg" alt="Reviewed on agentmods" width="80" height="20"></a>

Per session 95 Skills are progressive disclosure: only the name and description are preloaded; the body loads when the skill is used.

When invoked 4,500 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. Third-party audits

NVIDIA SkillSpector warn 7 Sept 2026

SkillSpector: 1 finding, up to medium

These are SkillSpector’s own severities. On a checked sample its high-severity flags on skills were ~96% false positives — a documented command, a public API, a “never do X” rule — so we show them as a caution to read, not a verdict. Why →

medium Agent Snooping · line 317
Skill enumerates or reads other installed skills. Access to other skills' SKILL.md files or the skills directory reveals prompt instructions, capabilities, and secrets that should be invisible to peer skills.

Fix: Remove all code or instructions that list or read other skills' files or directories. Skills should operate independently; cross-skill access is a privilege escalation.

How audits are shown

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.

Model	Per session	Once invoked
Fable 5.1	$0.00095	$0.04500
Opus 5	$0.00048	$0.02250
Sonnet 5	$0.00019	$0.00900
Haiku 4.5	$0.00010	$0.00450

Measured 10d ago against content hash fc0bdf412dd9, method: parsed. Prices are Anthropic first-party input rates as of 2026-09-10, from the pricing page.

Security

Grade A, and why

fanfande-plugin-structure 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 10d 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.

.agents/skills/fanfande-plugin-structure/SKILL.md · 567 lines

How it starts

The opening of the file, as written. The whole thing — 567 lines — stays where its author put it; the contents beside it link to each section on GitHub.

Fanfande / Anybox Plugin Structure

Source Of Truth

Use this skill for the current plugin package format used in the Anybox codebase. The old Fanfande paths and .fanfande-plugin/plugin.json layout are historical unless the live target repo proves otherwise.

Treat these files as the implementation source when schema details may have changed:

packages/anyboxagent/src/plugin/plugin.ts
packages/anyboxagent/Test/plugin.test.ts
plugins/Anybox-Plugins/index.json
plugins/Anybox-Plugins/computer-use-windows/.anybox-plugin/plugin.json
plugins/Anybox-Plugins/scripts/convert-openai-plugins.mjs
plugins/Anybox-Plugins/anybox-plugin-development/docs/anybox-third-party-plugin-development.md

Prefer the running code in plugin.ts over older docs when they disagree.

Current Format Summary

The current built-in plugin registry is an expanded source tree:

plugins/Anybox-Plugins/
  index.json
  <plugin-id>/
    .anybox-plugin/
      plugin.json
    skills/
    connectors/
    scripts/
    docs/
    assets/
    web/

Important rules:

Put the canonical manifest at <plugin-id>/.anybox-plugin/plugin.json.
Keep runtime code and content directories at the plugin root, as siblings of .anybox-plugin.
Do not use plugin.meta.json.
Do not commit zip artifacts to the built-in expanded registry.
plugins/Anybox-Plugins/index.json is a JSON array of direct HTTPS .anybox-plugin/plugin.json URLs.
Directory registry URLs are not supported.
Root plugin.json and .codex-plugin/plugin.json remain parser compatibility inputs, but are not the layout to generate for Anybox packages.
.fanfande-plugin/plugin.json is not the current Anybox runtime format.

Package Layout

For development, use a plugin source root whose children are plugin package folders:

ANYBOX_PLUGIN_LOCAL_DIR, when set.
Otherwise the agent data directory's plugins/local.

For managed installs, the runtime copies packages to:

ANYBOX_PLUGIN_INSTALL_DIR, when set.
Otherwise the agent data directory's plugins/installed.

Read the full file on GitHub · 567 lines

Files

What ships with it

1 file beside SKILL.md in the same directory: the scripts, references and assets a skill reads on demand. Not counted in the per-session cost; read them before you install if any of them is executable.

agents/openai.yaml 240 B

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.

10d ago First seen · 567 lines · 95 tokens per session scan A fc0bdf412dd9

Subscribe to this mod's changes

fanfande-plugin-structure is a skill published in the GitHub repository fanfan-de/anybox (57 stars, last pushed 27d ago), licensed MIT. It adds 95 tokens to every session and 4,500 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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anybox: Skill for Codex