Anthropic’s New Claude Code Review Agent – A Full‑Open‑Source Workflow

Published: 2025‑11‑15
Video Source: Anthropic’s NEW Claude Code Review Agent (Full Open Source Workflow)

Anthropic has just rewritten how teams review AI‑generated code. Their Claude Code Review Agent replaces human line‑by‑line reviews with an AI‑driven pipeline that is now open‑source. If you’re drowning in AI‑generated pull requests, worried about hidden security bugs, or simply stuck waiting for a teammate to comment, this workflow can unlock massive velocity and reduce bottlenecks.

TL;DR

Claude Code Review Agent automates the bulk of code reviews.
Uses slash commands, sub‑agents, and GitHub Actions for a fully automated pipeline.
Open‑source tooling: copy‑and‑paste your own repo with minimal setup.
Key benefits: speed, consistency, security, and knowledge transfer.

1. The Problem: Manual Review Bottleneck

Traditional Flow	AI‑Driven Flow
Engineer writes code → PR → Human review → Merge	Engineer writes code → PR → AI review (Claude) → Human acceptance testing → Merge

Volume spike: AI code generators produce larger PRs.
Quality control: Need to catch subtle hallucinations, security gaps, and style violations.
Manual effort: Line‑by‑line reviews become a time‑consuming bottleneck.

Anthropic’s Cloud Code team realized that Claude is usually right and that large PRs can be safely handed to an AI for the heavy lifting.

2. The Anthropic Solution: An Agentic Review Flow

Automated AI Review
- Runs security scanning, bug detection, style checks, and syntax validation.
- Think of it as a lint‑tool on steroids.
Human Acceptance Testing
- Reviewers focus on architecture, UX, business logic, and alignment with design mock‑ups.
- Less time on nit‑picks, more on high‑level decisions.
Iterative Feedback Loop
- AI can iterate on a PR multiple times before the human steps in, reducing the back‑and‑forth cycle.

3. Core Components of the Open‑Source Workflow

Component	Purpose	How to Use
Slash Commands (`/review`, `/security-review`)	Trigger AI reviews directly in PR comments.	Run from the PR comment thread.
Sub‑Agents	Execute specialized tasks (e.g., security audit) with isolated context.	Defined in `.cloud.md` files.
GitHub Action Runners	Automate the review on CI, leaving no manual step.	Add YAML files to `.github/workflows/`.
`.cloud.md` Config	Store project‑specific rules, style guides, and knowledge bases.	Create a markdown file in your repo.
MCPs (Micro‑Co‑Processors)	Provide tools like `playwright`, `github` API access, or custom scripts.	Declared in the workflow config.

Tip: The open‑source repo includes a cloud-code-action workflow that you can drop into any repo with minimal tweaks.

4. Building Your Own Review Pipeline

Step 1: Install the GitHub App

curl -X POST https://api.github.com/user/installations \
  -H "Authorization: token YOUR_GITHUB_TOKEN" \
  -d '{"app_id": YOUR_APP_ID}'

Anthropic provides a slashinstall github app command that opens a quick wizard.

Step 2: Add the `.cloud.md` File

# .cloud.md
review:
  - security
  - style
  - lint
  - architecture

Add your own context (docs, architecture diagrams, style guides) to help Claude understand your codebase.

Step 3: Create GitHub Actions

# .github/workflows/code-review.yml
name: Code Review
on:
  pull_request:
    types: [opened, synchronize]

jobs:
  review:
    runs-on: ubuntu-latest
    steps:
      - uses: actions/checkout@v4
      - uses: anthropic/cloud-code-action@v1
        with:
          model: claude-3-5-sonnet-20240620
          sub-agent: security-review

Step 4: Trigger a Review

# In a PR comment
/review

Claude will analyze the diff, comment on issues, and optionally open a new PR with suggested changes.

5. Mental Models & Best Practices

Model	What It Helps With	Practical Example
Inner Loop / Outer Loop	Inner: Rapid AI iterations; Outer: CI‑driven final check	Use slash commands for quick feedback; GitHub Actions for formal audit
Context, Tools, Validators	Context: prompts + docs; Tools: MCPs; Validators: example outputs	Provide a mock‑up image and a “good vs bad” code snippet in the `.cloud.md`
Knowledge Transfer	Store team expertise in markdown files	Import a shared `.cloud.md` from a senior engineer or a public repo
Role‑Based Prompting	Give Claude a specific persona	“You are a staff SRE focused on security”

6. Security Review Highlights

Automatic detection of hard‑coded secrets (e.g., fake API keys in the demo).
Severity rating (low/medium/high) with actionable comments.
False‑positive filtering – you can whitelist patterns that are known safe.
GitHub MCP writes comments directly on the PR, pointing to exact lines.

7. Extending Beyond Code Review

Product Management – AI can validate feature specs against acceptance criteria.
Data Engineering – Use sub‑agents for ETL pipeline linting.
UI/UX – Combine vision modalities (screenshots) with playwright to compare against mock‑ups.

Anthropic’s open‑source ecosystem already contains dozens of slash commands and sub‑agent templates that you can mix & match.

8. Getting Started Quickly

Clone the Open‑Source Repo
git clone https://github.com/anthropic/cloud-code-action.git
Copy the Example Workflows to your repo’s .github/workflows/.
Add a .cloud.md with your team’s style guide.
Run a PR – watch Claude comment automatically.

Pro Tip: Use the deep research report workflow to auto‑generate a security review prompt tailored to your startup’s domain.

9. Summary

Anthropic’s new Claude Code Review Agent turns the daunting task of reviewing AI‑generated code into a streamlined, automated process. By combining:

Slash commands for instant feedback,
Sub‑agents for specialized audits,
GitHub Actions for CI‑driven validation, and
Markdown‑based knowledge bases for context,

teams can dramatically reduce review time, catch security holes early, and maintain consistent coding standards—all while freeing human reviewers to focus on higher‑value decisions.

Ready to give your team a velocity boost? Grab the open‑source tooling, plug in your own .cloud.md, and let Claude do the heavy lifting.

Want More?

Claude Code Designer – Learn how to use vision modalities to iterate on UI designs.
Community Resources – Check out the Anthropic cloud‑code-action repo and the community‑built cloud‑code-templates collection.

Happy coding, and may your PRs be fast, clean, and secure!