Codex vs Claude Code: AI Code Review Compared

Codex is my starting point for routine GitHub reviews when its serious-issue focus fits the job. Managed Claude Code Review is worth comparing when your team wants adjustable review depth and verification by several agents, with separate usage billing. Both can find bugs; neither turns a clean report into proof that a pull request is safe.

I run Codex reviews in our release workflows and use Claude Code as the daily coding environment. That is not a claim that I have benchmarked Anthropic's managed reviewer. For the wider shortlist, see my AI code review tools guide.

At a Glance

Comparison criterion	Codex	Claude Code Review
Review threshold	P0/P1 default on GitHub; P2 on request	Important, Nit, Pre-existing
Pipeline	Repository-aware GitHub review	Multi-agent with verification
Rules	AGENTS.md	REVIEW.md and CLAUDE.md
Manual trigger	@codex review	@claude review
Availability	Qualifying ChatGPT plans	Team and Enterprise
Review charge	Plan allowance and credits	Separate token-based usage credits
Review time	No duration commitment	Varies with review level and change
Failed run	No published retry contract	Neutral; retry depends on failure

The practical choice is between a focused review drawing on your Codex allowance and a separately billed Claude service with Quick, Standard and Deep levels. Standard is Claude’s default. A higher setting buys more analysis, not a guarantee of more useful findings.

Which Codex and Claude Review Options Are Being Compared?

Codex has a managed GitHub reviewer, local review in Codex clients, and a codex-action building block for GitHub Actions. Claude Code has a managed GitHub App, the /code-review command, and Claude Code Action. Each option has its own setup and costs.

With managed review, the vendor runs the review service. OpenAI controls the Codex GitHub review threshold and posts the review through its connected cloud service. Anthropic runs its fleet and verification work on Anthropic infrastructure, then posts a neutral check with findings.

Local review gives one developer a private pass before the pull request. With an action, your team configures the runner, trigger, instructions, provider, permissions and how findings are posted. Comparing a local review with a managed review also means comparing different setup work, permissions and costs.

The managed GitHub services review pull requests on your repository. Local reviews and team-owned actions require a different setup. Use the Codex guide and Claude Code review guide when the decision is local review or a team-owned action.

Check which service your subscription pays for. A Claude Code subscription used for daily local work does not include managed review spend, and an OpenAI API key does not unlock native Codex GitHub review. Team-owned actions create their own provider and runner bills.

What Do Codex and Claude Code Review Check?

Codex reviews changed code with repository guidance and defaults to P0/P1 findings on GitHub, with P2 available on manual request. Managed Claude Code Review investigates bugs through multiple agents and verification, with Quick, Standard and Deep levels. These settings describe intended coverage, not guaranteed accuracy.

Anthropic says managed Code Review analyses the diff with surrounding full-codebase context. Specialised agents look for logic errors, security vulnerabilities, broken edge cases, and regressions, then a verification step checks candidate findings before posting them. Findings are classified as Important, Nit, or Pre-existing.

The products use different rules for deciding which findings to post. Codex filters the posted review to its two highest priorities. Claude uses a wider severity vocabulary and lets teams tune scope and reporting through REVIEW.md, within its protected review constraints. Try both on the same code before deciding which finds more useful bugs.

How Do You Configure Codex and Claude Code Review?

Configure Codex review guidance in applicable AGENTS.md files. Managed Claude Code Review uses REVIEW.md and CLAUDE.md; its review instructions come from the base or default branch, not the proposed head branch.

## Code Review Rules

- Report tenant writes without organisation scoping.
- Cite the unprotected execution path.
- Ignore formatting already enforced by CI.

Managed Claude Code Review uses CLAUDE.md for project context and REVIEW.md for review guidance. It reads review instructions from the base or default branch, never from the pull request’s own changes. Directory-level guidance can narrow the rules for particular code. Keep essential rules in the file itself because @ imports are not expanded.

The local /code-review command is a separate workflow. Anthropic says local review follows CLAUDE.md but does not read REVIEW.md. Teams should avoid assuming a rule tested locally will govern the managed GitHub service in the same way.

Pricing

Codex GitHub review is available through qualifying ChatGPT plans. Plus starts at $20 per month and includes cloud integrations such as automatic code review. OpenAI also lets eligible users buy credits to extend usage, so "included" describes an allowance rather than unlimited zero-cost review.

API-key access does not include GitHub cloud review. It supports Codex through the CLI, SDK, IDE extension, or custom automation, billed under the API rather than the native GitHub integration.

OpenAI's live rate card now separates most workspaces on token-based credit rates from a small Enterprise group still on its legacy card. The older estimate of roughly 34 credits per pull request appears only in that legacy section. Check the workspace's Codex Usage panel before forecasting review volume.

Anthropic bills managed Code Review to the organisation through token-based usage credits, separately from the Team or Enterprise plan’s included usage. There is no flat per-review price. Review level, change size, surrounding code and verification work affect the bill. The current billing documentation explains the spend limits.

Published plan terms.

Dimension	Codex review	Claude Code Review
Access path	Qualifying ChatGPT plans	Team and Enterprise
Published price	Plus from $20/mo	Variable token-based cost
Billing unit	Plan allowance, then credits	Usage credits per review
Off the integration	CLI, SDK, IDE extension	Local review command

A trigger changes the Claude bill directly. Once-after-creation runs once, every-push can multiply reviews, and manual mode waits for @claude review. Anthropic provides a spend cap and per-repository cost reporting. Codex also has finite plan usage, so both trials need an actual cost record.

Can Codex or Claude Code Review Control Merges?

Neither managed Codex review nor managed Claude Code Review provides a documented replacement for required human approval. Claude findings do not produce a failing check; Codex’s review comments likewise should not be treated as an autonomous approval. Keep branch protection and tests as the merge controls.

Start either trial with one review after the pull request is ready. Keep tests and human approval unchanged, then record accepted defects, dismissals, duplicate comments, elapsed time, and credits or usage spend. The shared triage definitions live on the AI code review comparisons hub.

Keep a second reviewer only if the extra bugs it catches justify its cost and the wait.

The Claude command you choose affects how often you pay for a review. @claude review and @claude review once both start one run without subscribing, while @claude review always subscribes the pull request to reviews on later pushes. Repeat billing is opt-in, so the repository trigger setting decides most of the cost.

Codex automatic review runs when a new pull request is opened for review. Manual @codex review is easier to line up with the exact commit a team wants inspected. Record the head commit beside each result so a later patch cannot make an old review look current.

What Happens When a Codex or Claude Review Fails?

Claude Code Review retries an interrupted session once automatically, but other failures need a new request; OpenAI does not publish an equivalent retry contract for managed Codex review. Check that either review completed before relying on an empty findings list.

For other failed or timed-out Claude runs, use @claude review or the GitHub Re-run button where supported; Re-run is unavailable for forks. Neither manual recovery subscribes the pull request to later pushes. Reaching the monthly spend cap creates a separate skipped-review comment. Check the reason before treating a missing review as a completed one.

OpenAI documents the normal Codex request and automatic paths but does not publish the same retry contract on its GitHub review page. The pilot should record the reaction, final review, elapsed time, and head commit. Someone needs to chase up a missing or outdated review. Neither means the code passed.

Test one visible review failure before a wider rollout. Trigger a review where the connected app lacks a needed repository permission, then confirm what the author and release reviewer can see. Record how long recovery takes. A review that silently fails cannot help you catch bugs.

What Access Do Codex and Claude Code Review Need?

Managed Codex and Claude Code Review require a repository connection to their cloud service. Keep review permission separate from branch-write permission. A reviewer can produce useful findings without receiving authority to alter the source branch.

OpenAI also allows a follow-up Codex task to prepare a fix when the connection has write access. That is a second decision after a finding has been proved. Review the generated patch, rerun tests, and request a fresh review on the new head.

Anthropic’s managed service is unavailable with Zero Data Retention, HIPAA configuration or customer-managed encryption keys. Team and Enterprise administrators choose repositories and a spend cap. If those terms do not fit, Claude Code Action is a different path that runs on a team-owned GitHub Actions runner and calls a configured model provider.

A custom action can narrow workflow permissions and network access, but the team then owns the prompt, secrets, event filters, output posting, and provider account. Include that maintenance work when comparing the action's cost with a managed service.

How Should You Compare Codex and Claude Review Results?

Compare Codex and Claude Code Review on the same pull requests, using changes with known outcomes. Include an authorisation path, a migration, a cross-file contract, a generated-file edit, and a routine fix. Keep tests and human approval unchanged so misses remain visible.

1. Request both managed reviews on the same ready commit.
2. Record the head commit, trigger, rules, elapsed time, and spend.
3. Label confirmed defects, wrong findings, repeats, and misses.
4. Check whether each finding names a reachable path and evidence.
5. Make one rules-file adjustment for each service.
6. Repeat the same cases and compare the results.

Record the review mode and trigger schedule for each tool. A local Claude pass and a managed Codex review can be legitimate alternatives, but their different permissions, context and costs must be part of the decision. For a direct managed-service comparison, use the same pull requests and trigger schedule.

After a finding causes a fix, rerun the relevant test and then the reviewer on the new commit. An old review cannot approve code it never saw. That matters especially when a second review adds delay and a separate usage charge.

The AI code review tools compared guide explains the shared finding labels.

The Codex and Claude Code Verdict

I would keep Codex as the normal GitHub reviewer where its P0/P1 focus and plan allowance fit. I would trial managed Claude Code Review on higher-risk changes to see whether its verification and adjustable depth add useful findings. Paying for both makes sense only if the second review earns its cost and the extra wait.

Frequently Asked Questions

Does Claude Code Review block a merge?

Claude Code Review does not block a merge or provide a required approval. Its findings do not make the check fail, so teams still need human approval and their own tests or policy checks.

Can an API key use Codex GitHub review?

An OpenAI API key does not unlock native Codex GitHub review; that cloud feature requires qualifying ChatGPT access. An API key can still support Codex in the CLI, SDK, IDE extension, or a custom scripted workflow.

What should Claude Code Review’s REVIEW.md contain?

Claude Code Review’s REVIEW.md should contain repository-specific review rules, such as paths to skip, checks that need project context and the evidence expected with a finding. The managed service reads trusted branch versions of this file rather than the pull request’s changes.

Read the Full Guides

• Codex review guide for GitHub and local review setup.
• Claude Code review guide for managed reviews, GitHub Actions and local reviews.
• AI code review comparisons hub for the shared evaluation method.