code-reviewer

A code-review guide is a checklist for examining code changes for correctness, security, readability, performance, error handling, and tests. A code review is the process of checking changes before they are merged into a project.

In plain words
What is it for?
Use it to review files or pull requests, investigate code quality, check web security issues, assess error handling, and look for missing tests or performance problems.
Why use it?
It helps uncover bugs, exposed secrets, unsafe input handling, weak tests, and maintainability problems before they reach users. It also gives review comments a consistent structure and severity.

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/nodnarbnitram/claude-code-extensions/code-reviewer
Any agent
npx skills add nodnarbnitram/claude-code-extensions --skill code-reviewer
Clone the repo
git clone --depth 1 https://github.com/nodnarbnitram/claude-code-extensions

Made for: Claude Code, Codex.

Per session 36 Skills are progressive disclosure: only the name and description are preloaded; the body loads when the skill is used.
When invoked 508 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 $0.00036 $0.00508
Opus 5 $0.00018 $0.00254
Sonnet 5 $0.00007 $0.00102
Haiku 4.5 $0.00004 $0.00051

Measured 2d ago against content hash df444a49ba9c, method: parsed. Prices are Anthropic first-party input rates as of 2026-08-30, from the pricing page.

Security

Grade A, and why

code-reviewer 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.

.claude/skills/code-reviewer/SKILL.md · 81 lines

How it starts

The opening of the file, as written. The whole thing — 81 lines — stays where its author put it; the contents beside it link to each section on GitHub.

Code Reviewer

Perform comprehensive code reviews focusing on quality, security, and maintainability.

Instructions

  1. Read the target files using the Read tool
  2. Search for patterns and related code using Grep
  3. Find related files using Glob
  4. Analyze code against the review checklist
  5. Provide structured feedback with severity levels

Review Checklist

Code Quality

  • Code is simple and readable
  • Functions and variables are well-named
  • No duplicated code (DRY principle)
  • Appropriate comments for complex logic
  • Consistent code style

Security

  • No exposed secrets or API keys
  • Input validation implemented
  • SQL injection prevention
  • XSS prevention for web code
  • Proper authentication/authorization checks

Error Handling

  • Errors are caught and handled appropriately
  • Meaningful error messages
  • No silent failures
  • Proper logging for debugging

Performance

  • No obvious performance bottlenecks
  • Efficient algorithms and data structures
  • Appropriate caching where needed
  • Database queries are optimized

Testing

  • Adequate test coverage
  • Edge cases are tested
  • Tests are readable and maintainable

Output Format

Organize feedback by severity:

Critical (Must Fix)

Issues that could cause security vulnerabilities, data loss, or crashes.

Warning (Should Fix)

Issues that could cause bugs, poor performance, or maintenance problems.

Suggestion (Consider)

Improvements for readability, consistency, or best practices.

Example Feedback

### Critical
- **SQL Injection vulnerability** in `user_service.py:45`
  - User input passed directly to query without sanitization
  - Fix: Use parameterized queries

### Warning
- **Missing error handling** in `api_client.py:23`
  - Network errors will crash the application
  - Fix: Add try/catch with appropriate error response

### Suggestion
- Consider extracting the validation logic in `validators.py:78-95` into a separate function for reusability

Read the full file on GitHub · 81 lines

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 · 81 lines · 36 tokens per session scan A df444a49ba9c

Subscribe to this mod's changes

code-reviewer is a skill published in the GitHub repository nodnarbnitram/claude-code-extensions (16 stars, last pushed 4mo ago), licensed MIT. It adds 36 tokens to every session and 508 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 2026-08-30.

Related

Other skills, from other repositories

systematic-debugging

Use when encountering any bug, test failure, or unexpected behavior, before proposing fixes.

obra/superpowers · 21 tokens

next-cache-components-adoption

Turn on Cache Components in a Next.js app and resolve the blocking routes it surfaces. Use when the user wants to enable, adopt, or migrate to Cache Components, flip the cacheComponents flag, work through a flood of blocking-prerender / instant validation errors, run the cache-components-instant-false codemod, or…

vercel/next.js · 95 tokens

babysit-pr

Babysit a GitHub pull request after creation by continuously polling review comments, CI checks/workflow runs, and mergeability state until the PR is merged/closed or user help is required. Diagnose failures, retry likely flaky failures up to 3 times, auto-fix/push branch-related issues when appropriate, and keep…

openai/codex · 114 tokens

imagegen

Generate or edit raster images when the task benefits from AI-created bitmap visuals such as photos, illustrations, textures, sprites, mockups, or transparent-background cutouts. Use when Codex should create a brand-new image, transform an existing image, or derive visual variants from references, and the output…

openai/codex · 113 tokens

cpu-profile-analysis

Analyze V8/Chrome CPU profiles (.cpuprofile) and DevTools trace files (Trace-.json). Use when: profiling performance, investigating slow functions, comparing code paths, finding bottlenecks, analyzing timeToRequest, understanding call trees from sampling profiler data, analyzing layout/paint/rendering, investigating…

microsoft/vscode · 71 tokens

next-cache-components-optimizer

Drive a Next.js route to instant navigation by setting up an agentic loop, under Cache Components / PPR, on initial load (hard navigation) and client-side navigation (soft navigation). Encode the goal as a failing @next/playwright instant() e2e and work it to green, one verified route at a time; the shipped test then…

vercel/next.js · 170 tokens