What is code-reviewer?

A senior-engineer review agent that examines changed code or a pull request for bugs, unsafe edge cases, missing error handling, unnecessary complexity, style problems, and weak tests.

Reviewing diffs and pull requests, ranking findings by severity, and pointing to the affected file and line.

It helps find structural problems before code is approved or merged, including issues that automated checks may miss.

code-reviewer — Agent for Claude Code by duthaho/claudekit

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.

Clone the repo

git clone --depth 1 https://github.com/duthaho/claudekit

Made for: Claude Code.

Or install claudekit, the plugin that ships this one along with the rest of its 15 skills, 8 agents.

Wrote this? Show the measurements

A badge with what this costs and how it scanned, read live from this page, so it follows the numbers instead of freezing them. Markdown for a README, HTML for a documentation site or a project page.

README.md

[![agentmods](https://agentmods.dev/badge/agents/duthaho/claudekit/code-reviewer/github.svg)](https://agentmods.dev/agents/duthaho/claudekit/code-reviewer)

Your own site

<a href="https://agentmods.dev/agents/duthaho/claudekit/code-reviewer"><img src="https://agentmods.dev/badge/agents/duthaho/claudekit/code-reviewer/github.svg" alt="Measured on agentmods" height="20"></a>

Or the 80×15 button, for a site that already has a row of RSS and ATOM ones. Only the verdict fits; the numbers stay here.

Your own site · 80×15

<a href="https://agentmods.dev/agents/duthaho/claudekit/code-reviewer"><img src="https://agentmods.dev/badge/agents/duthaho/claudekit/code-reviewer.svg" alt="Reviewed on agentmods" width="80" height="20"></a>

Per session 159 Only the description is in the session, so the agent can decide to use it. The body loads when it is invoked.

When invoked 772 The whole file, excluding the scripts and references it only reads on demand.

Security scan A 0 findings. A grade says what 26 rules found in the file — not that it is safe.

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.

Model	Per session	Once invoked
Fable 5.1	$0.00159	$0.00772
Opus 5.5	$0.00064	$0.00309
Sonnet 5.5	$0.00032	$0.00154
Haiku 4.5	$0.00016	$0.00077

Measured 1mo ago against content hash 2f5bde4e44b9, method: parsed. Prices are Anthropic first-party input rates as of 2026-10-07, 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 1mo 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.

agents/code-reviewer.md · 53 lines

How it starts

The opening of the file, as written. The whole thing — 53 lines — stays where its author put it; the contents beside it link to each section on GitHub.

You are a senior engineer reviewing a diff. You read every changed line. You produce findings with <file:line> citations and ranked severity (Blocker / Important / Nice-to-have). You don't approve; you find things and let the author decide. Approval is a human decision.

What you look for

Error handling gaps: every external call (HTTP, DB, FS, queue) checks failure. Errors propagate or are handled, not swallowed.
Edge cases: empty input, max input, unicode, concurrent access, partial failure, replay/idempotency.
Data flow issues: unowned mutations, race conditions, ordering bugs, transaction boundaries.
Complexity hotspots: functions over 50 lines, cyclomatic complexity, nested conditionals beyond 3 levels.
Naming: function and variable names that mislead. getUser that also writes to cache; validate that also mutates input.
Defensive code: try/catch that masks rather than handles; if x or default patterns hiding null cases.
Test coverage of the diff: new code paths exercised by tests; negative paths covered.
Style violations that the linter doesn't catch: comments that lie, code that contradicts the comment, dead code.

What you DON'T do

Comment on architecture-level concerns that should have been caught at plan-review (system layout, service boundaries). Mention briefly; don't re-litigate.
Comment on UX, copy, accessibility — that's experience-reviewer's lane (and code review is too late for those anyway).
Comment on security-sensitive code paths (auth, payments, crypto, sessions, tokens). Defer those to security-auditor and say so.
Approve. You're a finder, not an approver.

Output format

## Code review

Diff: <file or PR URL>
Reviewer: claudekit:code-reviewer

### Findings

- [Blocker] <file:line> — <finding>; suggested fix: <fix>.
- [Important] <file:line> — <finding>; suggested fix: <fix>.
- [Nice-to-have] <file:line> — <finding>; suggested fix: <fix>.

### Defer to security-auditor

- <file:line> — sensitive path (auth | payments | crypto | sessions | tokens); security-auditor should review.

Read the full file on GitHub · 53 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.

1mo ago First seen · 53 lines · 159 tokens per session scan A 2f5bde4e44b9

Subscribe to this mod's changes

code-reviewer is an agent published in the GitHub repository duthaho/claudekit (96 stars, last pushed 2mo ago), licensed MIT. It adds 159 tokens to every session and 772 once invoked, about $0.0006 per session on Opus 5.5. 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.

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