lean-review

lean-review is a skill for Claude Code from utk2103/Prompt-Studio. It costs 96 tokens per session (579 once invoked), scanned A, a copy of ponytail-review, Apache-2.0.

A code-review skill that looks specifically for unnecessary complexity, such as unused code, avoidable dependencies, and abstractions with no real need.

In plain words
What is it for?
Use it when reviewing a change for over-engineering, deciding what can be deleted, or checking whether a dependency, abstraction, or extra flexibility is justified.
Why use it?
It helps make a codebase smaller and easier to maintain by identifying parts that can be removed or replaced with simpler built-in options.

Skill for Claude Code

Written for Claude Code: shipped in a Claude Code plugin.

Part of the prompt-studio plugin — 9 skills, 3 agents shipped together

Good fit Use it when reviewing a change for over-engineering, deciding what can be deleted, or checking whether a dependency, abstraction, or extra flexibility is justified.

Compare 6 skills from other repositories ↓
Install with agentmods
npx agentmods add skills/utk2103/prompt-studio/lean-review
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 utk2103/Prompt-Studio --skill lean-review
Clone the repo
git clone --depth 1 https://github.com/utk2103/Prompt-Studio

Made for: Claude Code.

Or install prompt-studio, the plugin that ships this one along with the rest of its 9 skills, 3 agents.

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 lean-review

README.md
[![agentmods](https://agentmods.dev/badge/skills/utk2103/prompt-studio/lean-review/github.svg)](https://agentmods.dev/skills/utk2103/prompt-studio/lean-review)
Your own site
<a href="https://agentmods.dev/skills/utk2103/prompt-studio/lean-review"><img src="https://agentmods.dev/badge/skills/utk2103/prompt-studio/lean-review/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 lean-review

Your own site · 80×15
<a href="https://agentmods.dev/skills/utk2103/prompt-studio/lean-review"><img src="https://agentmods.dev/badge/skills/utk2103/prompt-studio/lean-review.svg" alt="Reviewed on agentmods" width="80" height="20"></a>
Per session 96 Skills are progressive disclosure: only the name and description are preloaded; the body loads when the skill is used.
When invoked 579 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 91% copy Near-identical to another mod 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 $0.00096 $0.00579
Opus 5 $0.00048 $0.00290
Sonnet 5 $0.00019 $0.00116
Haiku 4.5 $0.00010 $0.00058

Measured 9d ago against content hash 0cdae53b1143, method: parsed. Prices are Anthropic first-party input rates as of 2026-09-09, from the pricing page.

Security

Grade A, and why

lean-review 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 9d 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.

Origin

This is a copy

91% identical to ponytail-review — 14 lines differ, which has more behind it and is treated as the original. This page carries a canonical link to it rather than competing with it.

skills/lean-review/SKILL.md · 59 lines

What it actually says

Review diffs for unnecessary complexity. One line per finding: location, what to cut, what replaces it. The diff's best outcome is getting shorter.

Format

L<line>: <tag> <what>. <replacement>., or <file>:L<line>: ... for multi-file diffs.

Tags:

  • delete: dead code, unused flexibility, speculative feature. Replacement: nothing.
  • stdlib: hand-rolled thing the standard library ships. Name the function.
  • native: dependency or code doing what the platform already does. Name the feature.
  • yagni: abstraction with one implementation, config nobody sets, layer with one caller.
  • shrink: same logic, fewer lines. Show the shorter form.

Examples

❌ "This EmailValidator class might be more complex than necessary, have you considered whether all these validation rules are needed at this stage?"

L12-38: stdlib: 27-line validator class. "@" in email, 1 line, real validation is the confirmation mail.

L4: native: moment.js imported for one format call. Intl.DateTimeFormat, 0 deps.

repo.py:L88: yagni: AbstractRepository with one implementation. Inline it until a second one exists.

L52-71: delete: retry wrapper around an idempotent local call. Nothing replaces it.

L30-44: shrink: manual loop builds dict. dict(zip(keys, values)), 1 line.

Scoring

End with the only metric that matters: net: -<N> lines possible.

If there is nothing to cut, say Lean already. Ship. and stop.

Boundaries

Scope: over-engineering and complexity only. Correctness bugs, security holes, and performance are explicitly out of scope. Route them to a normal review pass, not this one. A single smoke test or assert-based self-check is the Lean minimum, not bloat, never flag it for deletion. Does not apply the fixes, only lists them. "stop lean-review" or "normal mode": revert to verbose review style.

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. 9d ago First seen · 59 lines · 96 tokens per session scan A 0cdae53b1143

Subscribe to this mod's changes

lean-review is a skill published in the GitHub repository utk2103/Prompt-Studio (7 stars, last pushed 8d ago), licensed Apache-2.0. It adds 96 tokens to every session and 579 once invoked, about $0.0005 per session on Opus 5. A static security scan graded it A with 0 findings. It is 91% identical to ponytail-review, differing in 14 lines, and is treated as a copy.

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