Code Reviewer by anthropics
Reviews code for bugs, logic errors, security vulnerabilities, code quality issues, and adherence to project conventions, using confidence-based filtering to report only high-priority issues that truly matter
- Type
- Subagent
- Repository
- anthropics/claude-plugins-official
- GitHub stars
- 37.1k
- License
- Apache-2.0
- Repo last updated
- Sep 25, 2026
- Source file
- plugins/feature-dev/agents/code-reviewer.md
- Model
- sonnet
What Code Reviewer by anthropics is
Code Reviewer by anthropics is a subagent published in the anthropics/claude-plugins-official repository on GitHub, which has about 37.1k stars. The repository describes itself as: “Official, Anthropic-managed directory of high quality Claude Code Plugins.”
A subagent is a specialist assistant that Claude can hand part of a task to. It is a markdown file whose frontmatter sets a name, a description that tells Claude when to delegate, and optionally the tools and model it may use; the body becomes the subagent's own system prompt.
Because a subagent works in its own context, it keeps the main conversation focused: Claude can send a narrow job, such as a review or a specialised analysis, to Code Reviewer and get back a compact result.
It is set up to use these tools: Glob, Grep, LS, Read, NotebookRead, WebFetch, TodoWrite, WebSearch, KillShell, BashOutput. Limiting tools is a good sign: the subagent can only do what those tools allow.
How to install Code Reviewer by anthropics
Claude Code
- Download code-reviewer.md from the repository.
- Save it to ~/.claude/agents/ to use it in every project, or to .claude/agents/ inside one project to share it through version control.
- Claude Code watches these folders, so the subagent is usually available right away. Ask Claude to use it by name, or @-mention it to make sure it runs.
Claude Cowork
- Cowork loads subagents through plugins. If the repository is packaged as a plugin marketplace, add it under Customize → Plugins → Add marketplace and install the plugin that contains this subagent.
- Otherwise, bundle the file into your own plugin's agents/ folder and upload it from Customize → Plugins.
New to extending Cowork? Our plugins guide and Customize guide explain how skills, plugins, and connectors fit together.
Inside the source file
An excerpt from plugins/feature-dev/agents/code-reviewer.md, shared under the repository's Apache-2.0 license. Read the full file on GitHub.
You are an expert code reviewer specializing in modern software development across multiple languages and frameworks. Your primary responsibility is to review code against project guidelines in CLAUDE.md with high precision to minimize false positives.
Review Scope
By default, review unstaged changes from git diff. The user may specify different files or scope to review.
Core Review Responsibilities
Project Guidelines Compliance: Verify adherence to explicit project rules (typically in CLAUDE.md or equivalent) including import patterns, framework conventions, language-specific style, function declarations, error handling, logging, testing practices, platform compatibility, and naming conventions.
Bug Detection: Identify actual bugs that will impact functionality - logic errors, null/undefined handling, race conditions, memory leaks, security vulnerabilities, and performance problems.
Code Quality: Evaluate significant issues like code duplication, missing critical error handling, accessibility problems, and inadequate test coverage.
Confidence Scoring
Rate each potential issue on a scale from 0-100:
- 0: Not confident at all. This is a false positive that doesn't stand up to scrutiny, or is a pre-existing issue.
- 25: Somewhat confident. This might be a real issue, but may also be a false positive. If stylistic, it wasn't explicitly called out in project guidelines.
- 50: Moderately confident. This is a real issue, but might be a nitpick or not happen often in practice. Not very important relative to the rest of the changes.
- 75: Highly confident. Double-checked and verified this is very likely a real issue that will be hit in practice. The existing approach is insufficient. Important and will directly impact functionality, or is directly mentioned in project guidelines.
- 100: Absolutely certain. Confirmed this is definitely a real issue that will happen frequently in practice. The evidence directly confirms this.
Only report issues with confidence ≥ 80. Focus on issues that truly matter - quality over quantity.
Output Guidance
Start by clearly stating what you're reviewing. For each high-confidence issue, provide:
- Clear description with confidence score
- File path and line number
- Specific project guideline reference or bug explanation
- Concrete fix suggestion
Group issues by severity (Critical vs Important). If no high-confidence issues exist, confirm the code meets standards with a brief summary.
Structure your response for maximum actionability - developers should know exactly what to fix and why.
Before you install
- Read the whole file first. Skills, commands, and subagents are instructions Claude will follow, so make sure they match what you want.
- Check which tools, scripts, or MCP servers it uses. Local servers and scripts run with your permissions.
- Try it in a test project or a copy of your files before pointing it at real work.
- Pin the version you tested, and review changes before updating.
- Watch for instructions that fetch web content or run shell commands; those are where prompt injection risks start. See our prompt injection guide.
FAQ
What is Code Reviewer by anthropics?
Code Reviewer by anthropics is a subagent for Claude Code and Claude Cowork from the anthropics/claude-plugins-official repository on GitHub. Reviews code for bugs, logic errors, security vulnerabilities, code quality issues, and adherence to project conventions, using confidence-based filtering to report only high-priority issues that truly matter
How do I install Code Reviewer by anthropics in Claude Code?
Download code-reviewer.md from the repository. Save it to ~/.claude/agents/ to use it in every project, or to .claude/agents/ inside one project to share it through version control. Claude Code watches these folders, so the subagent is usually available right away. Ask Claude to use it by name, or @-mention it to make sure it runs.
Can I use Code Reviewer by anthropics in Claude Cowork?
Cowork loads subagents through plugins. If the repository is packaged as a plugin marketplace, add it under Customize → Plugins → Add marketplace and install the plugin that contains this subagent. Otherwise, bundle the file into your own plugin's agents/ folder and upload it from Customize → Plugins.
Is Code Reviewer by anthropics safe to install?
It is a third-party community resource, not reviewed by Anthropic or this site. Read the source file first, check which tools and connectors it uses, and install only from sources you trust.
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