skill-subagent-usage

A rule encouraging agents to actively look for relevant skills and specialised subagents, which are focused helpers for independent parts of a task.

In plain words
What is it for?
Use it to decide when to inspect and apply a skill, when to delegate work to a subagent, and how to announce that choice before starting.
Why use it?
It reduces the chance that a task is handled without available expertise or useful parallel work.

Cursor rule for Cursor

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 rules/chachamaru127/claude-code-harness/skill-subagent-usage
Clone the repo
git clone --depth 1 https://github.com/Chachamaru127/claude-code-harness

Made for: Cursor.

Per session 230 This file is loaded in full into every session.
When invoked 230 The same file — it is already loaded in full.
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 $0.00230 $0.00230
Opus 5 $0.00115 $0.00115
Sonnet 5 $0.00046 $0.00046
Haiku 4.5 $0.00023 $0.00023

Measured 3d ago against content hash 4c37cfd57b6d, method: parsed. Prices are Anthropic first-party input rates as of 2026-08-30, from the pricing page.

Security

Grade A, and why

skill-subagent-usage 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 3d 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.

.cursor/rules/skill-subagent-usage.mdc · 19 lines

What it actually says

Skill と Subagent を積極活用する

使い分け

  • Skill: 専門知識が必要なタスク → 作業開始前に SKILL.md を読み、手順/制約をそのまま適用する。宣言だけで終わらせない。
  • Subagent: 独立コンテキストが有効なタスク(リファクタリング・レビュー・広範囲探索など)、または並列実行したい場合に委任する。

※ 両者は併用可。Skill の知識を Subagent に渡して実行することもある。 ※ 小さいタスクで該当する Skill/Subagent がない場合は、通常フローで進める。

利用時は明示

使用する Skill/Subagent と理由は1行で明記してから進める。

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. 3d ago First seen · 19 lines · 230 tokens per session scan A 4c37cfd57b6d

Subscribe to this mod's changes

skill-subagent-usage is a cursor rule published in the GitHub repository Chachamaru127/claude-code-harness (3,079 stars, last pushed 2d ago), licensed MIT. It adds 230 tokens to every session, about $0.0011 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.