explain

A code explanation guide that connects a file, function, class, or configuration setting to the surrounding project and its flow of data.

In plain words
What is it for?
Use it to understand a repository module, trace callers and dependencies, explain a symbol or file, and clarify the role of code in the project architecture.
Why use it?
It prevents explanations from treating a code fragment in isolation, which can hide who calls it, what it changes, and how it affects the user-facing result.

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/penwyp/claudepreference/explain
Any agent
npx skills add penwyp/ClaudePreference --skill explain
Clone the repo
git clone --depth 1 https://github.com/penwyp/ClaudePreference

Made for: Claude Code, Codex.

Per session 85 Skills are progressive disclosure: only the name and description are preloaded; the body loads when the skill is used.
When invoked 1,050 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 $0.00085 $0.01050
Opus 5 $0.00043 $0.00525
Sonnet 5 $0.00017 $0.00210
Haiku 4.5 $0.00009 $0.00105

Measured 2d ago against content hash 03fe830b5dc8, method: parsed. Prices are Anthropic first-party input rates as of 2026-08-30, 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 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.

skills/explain/SKILL.md · 89 lines

How it starts

The opening of the file, as written. The whole thing — 89 lines — stays where its author put it; the contents beside it link to each section on GitHub.

Explain

Explain the target in repository context, not in isolation. Always connect the local code to the surrounding call chain, owning module, upstream inputs, downstream effects, and user-visible responsibility.

Prefer evidence from the codebase. If a claim depends on inference, label it clearly as inference.

Input Decision

  1. Classify the input: code snippet → locate symbols in repo; file path → read file and expand to callers/callees; symbol name or implicit target → search repo for best match.
  2. Resolve ambiguity before explaining. If multiple matches, explain the best match and mention the ambiguity briefly.
  3. Keep scope aligned: a single-function question does not need a subsystem tour.

Analysis Workflow

  1. Read the target artifact.
  2. Expand one layer outward.
    • Check who imports it, who calls it, what it calls, which config or env values feed it, and what outputs or side effects it produces.
  3. Place it in project structure.
    • Identify whether it is an entry point, adapter, domain service, data model, UI component, CLI command, tool handler, scheduler job, test helper, or glue code.
  4. Extract the important parameters.
    • Prioritize constructor params, function args, config fields, env vars, callback hooks, flags, discriminators, and return objects.
  5. Explain why those parameters matter.
    • State what each important parameter controls, where it comes from, typical values, and what behavior changes when it is absent or changed.
  6. Summarize the role.
    • End with the target's responsibility in one sentence that a new contributor can keep in their head.

What To Explain

  • The target's direct responsibility.
  • Why it exists in this project.
  • Where it sits in the call path or module graph.
  • What invokes it and what it invokes.
  • What data it consumes and produces.
  • Which parameters are key and which are incidental.
  • What would break or change if a key parameter changed.
  • Whether it is framework boilerplate, business logic, integration glue, or cross-cutting infrastructure.

Read the full file on GitHub · 89 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.

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 · 89 lines · 85 tokens per session scan A 03fe830b5dc8

Subscribe to this mod's changes

explain is a skill published in the GitHub repository penwyp/ClaudePreference (137 stars, last pushed 3mo ago), licensed MIT. It adds 85 tokens to every session and 1,050 once invoked, about $0.0004 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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