Agent skill

Review And Simplify Changes

by Dimillian in Dimillian/Skills

Review a git diff or explicit file scope for reuse, code quality, efficiency, clarity, and standards issues, then optionally apply safe Codex-driven fixes.

MITAuto-check passedDevelopment

Install Review And Simplify Changes

skills CLI
$ npx skills add Dimillian/Skills --skill review-and-simplify-changes -a claude-code

Project install by default; add -g for ~/.claude/skills/.

GitHub CLI
$ gh skill install Dimillian/Skills review-and-simplify-changes --agent claude-code

Project scope by default; add --scope user for a personal install. Needs GitHub CLI 2.90.0 or later (public preview).

Manual copy
$ git clone --depth 1 https://github.com/Dimillian/Skills.git skills-src && mkdir -p .claude/skills && cp -r skills-src/review-and-simplify-changes .claude/skills/review-and-simplify-changes && rm -rf skills-src

Use ~/.claude/skills/ instead of .claude/skills for a personal install. The folder must contain SKILL.md.

Claude Code skills documentation · loads skills from .claude/skills/

Facts

Skill name
review-and-simplify-changes
GitHub stars
4k
Token cost
~2k tokens
SKILL.md length
1,106 words
Files
1
Skills in repo
12
Repo updated
First seen
Licence
MIT

At a glance

Review a git diff or explicit file scope for reuse, code quality, efficiency, clarity, and standards issues, then optionally apply safe Codex-driven fixes.

  • Works in 6 steps: Determine the Scope and Diff Command → Launch Four Read-Only Review Sub-Agents… → Aggregate Findings → …
  • The user asks to simplify code
  • SKILL.md covers Modes, Step 1: Determine the Scope…, Step 2: Launch Four Read-Only… and Step 3: Aggregate Findings, plus 3 more sections
  • Calls git

What it does

Review And Simplify Changes is an agent skill from Dimillian/Skills. Review a git diff or explicit file scope for reuse, code quality, efficiency, clarity, and standards issues, then optionally apply safe Codex-driven fixes. Use when the user asks to "simplify code", "review changed code", "check for code reuse", "review code quality", "review efficiency", "simplify changes", "clean up code", "refactor changes", or "run simplify".

Its SKILL.md is about 2k tokens, which your agent loads only when the skill is triggered. It is a single SKILL.md file with no bundled scripts.

It sits in Development, covering Refactoring, Subagents and Code quality. It works with Git. The licence is MIT.

When your agent uses it

  • The user asks to simplify code
  • Review changed code
  • Check for code reuse
  • Review code quality

Example prompts

  • “simplify code”
  • “review changed code”
  • “check for code reuse”
  • “/review-and-simplify-changes”

Workflow steps

6 steps, taken from the step headings in SKILL.md.

  1. Determine the Scope and Diff Command
  2. Launch Four Read-Only Review Sub-Agents in Parallel
  3. Aggregate Findings
  4. Fix Issues Carefully
  5. Validate When Required
  6. Summarize Outcome

What it can do on your machine

Read from SKILL.md and the folder at commit 05ba982. It shows what the files ask for, not the result of running them.

  • Tool permissions

    Pre-approves nothing: there is no allowed-tools line, so your agent's usual permission prompts apply.

    From allowed-tools in the SKILL.md frontmatter.

  • Runs code

    Shell commands in SKILL.md call:

    • git

    From the folder's file list and the shell code blocks in SKILL.md.

  • Network

    No URLs in SKILL.md. Its commands use git, which can reach the network depending on how they are called.

    From URLs in SKILL.md, links to its own repository left out.

  • Credentials

    Names no API keys, tokens, secrets or passwords.

    From names ending in _API_KEY, _TOKEN, _SECRET, _KEY or _PASSWORD in SKILL.md.

Context cost

Review And Simplify Changes loads about 2k tokens when it runs. Until then it costs about 98 tokens; SKILL.md has 1,106 words of instructions outside code blocks.

Always · name and description, kept in context so the agent knows when to use it
~98
When it runs · the whole SKILL.md, loaded when a task matches
~2k

Estimates: characters ÷ 4, the usual rule of thumb; real counts depend on the model's tokenizer. Scripts and assets cost tokens only if the agent reads them.

Safety

Auto-check passed

The automated check found no risky patterns in SKILL.md.

Automated static check — not a guarantee. Review scripts before installing. It scans the text of SKILL.md for risky patterns (piping downloads into a shell, reading credential files, hidden Unicode, destructive commands); files beside SKILL.md are not scanned.

SKILL.md

The full file from Dimillian/Skills at commit 05ba982, republished under its MIT licence (© Dimillian). 1,106 words, ~1,966 tokens.

Download SKILL.mdSave it as .claude/skills/review-and-simplify-changes/SKILL.md (or your agent's skills folder).
name
review-and-simplify-changes
description
Review a git diff or explicit file scope for reuse, code quality, efficiency, clarity, and standards issues, then optionally apply safe Codex-driven fixes. Use when the user asks to "simplify code", "review changed code", "check for code reuse", "review code quality", "review efficiency", "simplify changes", "clean up code", "refactor changes", or "run simplify".

Review and Simplify Changes

Review changed code for reuse, quality, efficiency, and clarity issues. Use Codex sub-agents to review in parallel, but keep those sub-agents read-only: they should only inspect code and send findings back to the main agent. Only the main agent may apply high-confidence, behavior-preserving fixes.

Modes

Choose the mode from the user's request:

  • review-only: user asks to review, audit, or check the changes
  • safe-fixes: user asks to simplify, clean up, or refactor the changes
  • fix-and-validate: same as safe-fixes, but also run the smallest relevant validation after edits

If the user does not specify, default to:

  • review-only for "review", "audit", or "check"
  • safe-fixes for "simplify", "clean up", or "refactor"

Step 1: Determine the Scope and Diff Command

Prefer this scope order:

  1. Files or paths explicitly named by the user
  2. Current git changes
  3. Files edited earlier in the current Codex turn
  4. Most recently modified tracked files, only if the user asked for a review but there is no diff

If there is no clear scope, stop and say so briefly.

When using git changes, determine the smallest correct diff command based on the repo state:

  • unstaged work: git diff
  • staged work: git diff --cached
  • branch or commit comparison explicitly requested by the user: use that exact diff target
  • mixed staged and unstaged work: review both

Do not assume git diff HEAD is the right default when a smaller diff is available.

Before reviewing standards or applying fixes, read the repo's local instruction files and relevant project docs for the touched area. Prefer the closest applicable guidance, such as:

  • AGENTS.md
  • repo workflow docs
  • architecture or style docs for the touched module

Use those instructions to distinguish real issues from intentional local patterns.

Step 2: Launch Four Read-Only Review Sub-Agents in Parallel

Use Codex sub-agents when the scope is large enough for parallel review to help. For a tiny diff or one very small file, it is acceptable to review locally instead.

When spawning sub-agents:

  • give each sub-agent the same scope
  • tell each sub-agent to inspect only its assigned review role
  • tell each sub-agent it is operating in a read-only review pass
  • do not let sub-agents edit files, run apply_patch, stage changes, commit, or perform other state-mutating actions
  • ask for concise, structured findings only
  • ask each sub-agent to report file, line or symbol, problem, recommended fix, and confidence
  • ask each sub-agent to return findings to the main agent only; they must not implement fixes themselves

Use four review roles.

Sub-Agent 1: Code Reuse Review

Review the changes for reuse opportunities:

  1. Search for existing helpers, utilities, or shared abstractions that already solve the same problem.
  2. Flag duplicated functions or near-duplicate logic introduced in the change.
  3. Flag inline logic that should call an existing helper instead of re-implementing it.

This sub-agent is read-only. It must not edit files, apply patches, or make any other workspace changes.

Recommended sub-agent role: explorer for broad codebase lookup, or reviewer if a stronger review pass is more useful than wide search.

Sub-Agent 2: Code Quality Review

Review the same changes for code quality issues:

  1. Redundant state, cached values, or derived values stored unnecessarily
  2. Parameter sprawl caused by threading new arguments through existing call chains
  3. Copy-paste with slight variation that should become a shared abstraction
  4. Leaky abstractions or ownership violations across module boundaries
  5. Stringly-typed values where existing typed contracts, enums, or constants already exist

This sub-agent is read-only. It must not edit files, apply patches, or make any other workspace changes.

Recommended sub-agent role: reviewer

Sub-Agent 3: Efficiency Review

Review the same changes for efficiency issues:

  1. Repeated work, duplicate reads, duplicate API calls, or unnecessary recomputation
  2. Sequential work that could safely run concurrently
  3. New work added to startup, render, request, or other hot paths without clear need
  4. Pre-checks for existence when the operation itself can be attempted directly and errors handled
  5. Memory growth, missing cleanup, or listener/subscription leaks
  6. Overly broad reads or scans when the code only needs a subset

This sub-agent is read-only. It must not edit files, apply patches, or make any other workspace changes.

Recommended sub-agent role: reviewer

Show full SKILL.md (415 more words)Show less
Sub-Agent 4: Clarity and Standards Review

Review the same changes for clarity, local standards, and balance:

  1. Violations of local project conventions or module patterns
  2. Unnecessary complexity, deep nesting, weak names, or redundant comments
  3. Overly compact or clever code that reduces readability
  4. Over-simplification that collapses separate concerns into one unclear unit
  5. Dead code, dead abstractions, or indirection without value

This sub-agent is read-only. It must not edit files, apply patches, or make any other workspace changes.

Recommended sub-agent role: reviewer

Only report issues that materially improve maintainability, correctness, or cost. Do not churn code just to make it look different.

Step 3: Aggregate Findings

Wait for all review sub-agents to complete, then merge their findings.

The main agent owns this step. Treat sub-agent output as review input only, not as permission to delegate code changes back out.

Normalize findings into this shape:

  1. File and line or nearest symbol
  2. Category: reuse, quality, efficiency, or clarity
  3. Why it is a problem
  4. Recommended fix
  5. Confidence: high, medium, or low

Discard weak, duplicative, or instruction-conflicting findings before editing.

Step 4: Fix Issues Carefully

In review-only mode, stop after reporting findings.

In safe-fixes or fix-and-validate mode:

  • Only the main agent applies fixes for this skill
  • Apply only high-confidence, behavior-preserving fixes
  • Skip subjective refactors that need product or architectural judgment
  • Preserve local patterns when they are intentional or instruction-backed
  • Keep edits scoped to the reviewed files unless a small adjacent change is required to complete the fix correctly

Prefer fixes like:

  • replacing duplicated code with an existing helper
  • removing redundant state or dead code
  • simplifying control flow without changing behavior
  • narrowing overly broad operations
  • renaming unclear locals when the scope is contained

Do not stage, commit, or push changes as part of this skill.

Step 5: Validate When Required

In fix-and-validate mode, after the main agent finishes edits, run the smallest relevant validation for the touched scope.

Examples:

  • targeted tests for the touched module
  • typecheck or compile for the touched target
  • formatter or lint check if that is the project's real safety gate

Prefer fast, scoped validation over full-suite runs unless the change breadth justifies more.

If validation is skipped because the user asked not to run it, say so explicitly.

Step 6: Summarize Outcome

Close with a brief result:

  • what was reviewed
  • what was fixed, if anything
  • what was intentionally left alone
  • whether validation ran

If the code is already clean for this rubric, say that directly instead of manufacturing edits.

© Dimillian, MIT. Rendered from Markdown: HTML in the file is shown as text, images as links, and headings moved down two levels. Raw file

Files

Just SKILL.md in review-and-simplify-changes of Dimillian/Skills.

Open the folder on GitHubat commit 05ba982

Compare with similar skills

Review And Simplify Changes next to the 5 skills that share the most tags, products or categories with it. Stars are the repository's; “used in” counts other GitHub owners with a copy.

Review And Simplify Changes compared with similar skills
SkillStarsUsed inTokensAuto-checkLicenceRepo updated
Review And Simplify Changes this skillDimillian/Skills4k—~2kAutomated safety check: PassMIT
Code Revieweralirezarezvani/claude-code-tresor777—~1.8kAutomated safety check: PassMIT
Code SimplifierTwiTech-LAB/devchain101—~2kAutomated safety check: PassCustom licence
Simplify Recent ChangesQwenLM/qwen-code28k—~1.3kAutomated safety check: PassApache-2.0
Simplify Codesickn33/agentic-awesome-skills47k2 repos~1.8kAutomated safety check: PassMIT
Code SimplifierOpenHands/extensions158—~1.3kAutomated safety check: PassMIT

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Works with

Categories

Questions about Review And Simplify Changes

What does Review And Simplify Changes do?

Review a git diff or explicit file scope for reuse, code quality, efficiency, clarity, and standards issues, then optionally apply safe Codex-driven fixes. Review And Simplify Changes is an agent skill from Dimillian/Skills. Review a git diff or explicit file scope for reuse, code quality, efficiency, clarity, and standards issues, then optionally apply safe Codex-driven fixes.

When should I use Review And Simplify Changes?

Review And Simplify Changes fits situations like: the user asks to simplify code; review changed code; check for code reuse; review code quality.

How do I install Review And Simplify Changes in Claude Code?

Run `npx skills add Dimillian/Skills --skill review-and-simplify-changes -a claude-code`. Or copy the skill folder (review-and-simplify-changes in Dimillian/Skills) into .claude/skills/review-and-simplify-changes in your project. Claude Code loads it when a task matches its description.

How do I install Review And Simplify Changes in Codex?

Run `npx skills add Dimillian/Skills --skill review-and-simplify-changes -a codex`. Or copy the skill folder (review-and-simplify-changes in Dimillian/Skills) into .agents/skills/review-and-simplify-changes in your project. Codex loads it when a task matches its description.

Can I use Review And Simplify Changes in Cursor, Gemini CLI or GitHub Copilot?

Cursor, Gemini CLI, GitHub Copilot and OpenCode also load SKILL.md folders. With the skills CLI, run `npx skills add Dimillian/Skills --skill review-and-simplify-changes -a cursor` (or -a gemini-cli, github-copilot or opencode for the others). To copy it by hand, put the folder in .cursor/skills/review-and-simplify-changes, .gemini/skills/review-and-simplify-changes, .github/skills/review-and-simplify-changes and .opencode/skills/review-and-simplify-changes in your project.

What does Review And Simplify Changes need to run?

Going by SKILL.md and its folder, Review And Simplify Changes needs the command-line tools its instructions call (git).

Does Review And Simplify Changes access the network?

SKILL.md contains no URLs. Its commands use git, which can reach the network depending on how they are called. This is read from the text; nothing was executed.

Is Review And Simplify Changes safe to install?

Our automated static check of SKILL.md found no risky patterns, such as piping downloads into a shell, reading credential files or hidden Unicode. It is not a guarantee. Review the folder before installing.

What licence does Review And Simplify Changes use?

Review And Simplify Changes is published under the MIT licence (the repository's licence). It allows redistribution, so the full SKILL.md is shown on this page.

How many tokens does Review And Simplify Changes use?

About 2k tokens (SKILL.md is roughly 7.9k characters). Agents keep only the skill's name and description in context until a task matches; then they load SKILL.md in full.

What are the alternatives to Review And Simplify Changes?

Skills that share tags, products or a category with Review And Simplify Changes: Code Reviewer (alirezarezvani/claude-code-tresor, 777 stars), Code Simplifier (TwiTech-LAB/devchain, 101 stars), Simplify Recent Changes (QwenLM/qwen-code, 28k stars) and Simplify Code (sickn33/agentic-awesome-skills, 47k stars). The comparison table on this page puts their stars, adoption, token cost, safety result and licence side by side.

Who maintains Review And Simplify Changes?

Dimillian (a GitHub user) maintains it in Dimillian/Skills, which has 3,985 GitHub stars. The repository holds 12 skills in this directory. The repository was last updated on March 29, 2026.

Source: Dimillian/Skills on GitHub. Facts on this page come from the repository at the commit we read; the author's words are quoted as theirs.