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.
npx agentmods add skills/azu/claude-code-plugins/react-you-might-not-need-an-effectnpx skills add azu/claude-code-plugins --skill react-you-might-not-need-an-effectgit clone --depth 1 https://github.com/azu/claude-code-pluginsWrote 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.
[](https://agentmods.dev/skills/azu/claude-code-plugins/react-you-might-not-need-an-effect)<a href="https://agentmods.dev/skills/azu/claude-code-plugins/react-you-might-not-need-an-effect"><img src="https://agentmods.dev/badge/skills/azu/claude-code-plugins/react-you-might-not-need-an-effect.svg" alt="Measured on agentmods" height="20"></a>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 | $0.00046 | $0.00611 |
| Opus 5 | $0.00023 | $0.00305 |
| Sonnet 5 | $0.00009 | $0.00122 |
| Haiku 4.5 | $0.00005 | $0.00061 |
Grade A, and why
react-you-might-not-need-an-effect 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 5d 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.
What it actually says
React: You Might Not Need an Effect
React公式ドキュメント「You Might Not Need an Effect」に基づき、不要なuseEffectを書かないようにする。
Instructions
Reactコンポーネントを書く・編集する際、useEffectを使う前に以下のパターンに該当しないか確認する。該当する場合はuseEffectを使わない代替案を採用する。
検出すべき12のアンチパターン
詳細は PATTERNS.md を参照。
React公式ドキュメントのパターン
| パターン | 問題 | 解決策 |
|---|---|---|
| 導出状態 | propsやstateから計算可能な値をstateで管理 | レンダリング時に計算 |
| 高コスト計算 | useEffectでキャッシュ | useMemoを使用 |
| propsでstate全体リセット | useEffectでリセット | keyを使用 |
| props変更で一部state調整 | useEffectで調整 | レンダリング中に調整 |
| イベントハンドラ処理 | useEffectでAPIコール | イベントハンドラで直接処理 |
| ロジック共有 | useEffectで共通処理 | 関数を抽出して共有 |
| 状態の連鎖更新 | useEffectのチェーン | イベントハンドラで一括更新 |
ESLintプラグイン追加パターン
| パターン | 問題 | 解決策 |
|---|---|---|
| 内部stateを親に渡す | useEffectでstateを親コールバックに渡す | stateを親にリフトアップ |
| 外部データを親に渡す | useEffectでフェッチデータを親に渡す | 親でデータ取得 |
| refを親に渡す | useEffectでref.currentを親に渡す | forwardRefを使用 |
| state初期化 | useEffect内でリテラル値でstate設定 | useStateの初期値で指定 |
| 空のuseEffect | 中身が空のuseEffect | 削除する |
References
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.
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.
- 5d ago First seen · 46 lines · 46 tokens per session scan A a2f9962af04a
react-you-might-not-need-an-effect is a skill published in the GitHub repository azu/claude-code-plugins (2 stars, last pushed 7mo ago), licensed MIT. It adds 46 tokens to every session and 611 once invoked, about $0.0002 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 2026-08-31.
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