explain

explain is a skill for Claude Code from fossuav/aap. It costs 39 tokens per session (608 once invoked), scanned A, original, GPL-3.0.

A skill for explaining how ArduPilot code, architecture, and subsystems work. ArduPilot is open-source software for controlling drones and other vehicles.

In plain words
What is it for?
Use it to explain a file, subsystem, architecture decision, or the path that data and control take through ArduPilot.
Why use it?
It helps developers understand unfamiliar files and code paths before changing or debugging them.

Skill for Claude Code

Written for Claude Code: allowed-tools in frontmatter.

Good fit Use it to explain a file, subsystem, architecture decision, or the path that data and control take through ArduPilot.

Compare 6 skills from other repositories ↓
Install with agentmods
npx agentmods add skills/fossuav/aap/explain
View source ↗ fossuav/aap
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 fossuav/aap --skill explain
Clone the repo
git clone --depth 1 https://github.com/fossuav/aap

Made for: Claude Code.

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 explain

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

Your own site · 80×15
<a href="https://agentmods.dev/skills/fossuav/aap/explain"><img src="https://agentmods.dev/badge/skills/fossuav/aap/explain.svg" alt="Reviewed on agentmods" width="80" height="20"></a>
Per session 39 Skills are progressive disclosure: only the name and description are preloaded; the body loads when the skill is used.
When invoked 608 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 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 5.1 $0.00039 $0.00608
Opus 5.5 $0.00016 $0.00243
Sonnet 5.5 $0.00008 $0.00122
Haiku 4.5 $0.00004 $0.00061

Measured 1mo ago against content hash 595e18ee8667, method: parsed. Prices are Anthropic first-party input rates as of 2026-10-07, from the pricing page.

Security

Grade A, and why

explain 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.

claude/skills/explain/SKILL.md · 60 lines

The source is not reproduced here

Licensed GPL-3.0

The repository is licensed GPL-3.0, which this catalogue does not treat as permission to reproduce the file. Read it at the source.

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. 1mo ago First seen · 60 lines · 39 tokens per session scan A 595e18ee8667

Subscribe to this mod's changes

explain is a skill published in the GitHub repository fossuav/aap (19 stars, last pushed 2d ago), licensed GPL-3.0. It adds 39 tokens to every session and 608 once invoked, about $0.0002 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 2026-08-30.