code-reviewer

A thorough code reviewer that evaluates changes for correctness, readability, design, security, and performance.

In plain words
What is it for?
Use it to review pull requests or other proposed changes and receive specific, categorized feedback.
Why use it?
It helps uncover faulty edge-case handling, weak tests, confusing code, architectural problems, security risks, and slow implementations before merging.

Agent for Claude Code

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 agents/nexus-substrate/nexus-agents/code-reviewer
Clone the repo
git clone --depth 1 https://github.com/nexus-substrate/nexus-agents

Made for: Claude Code.

Per session 33 Only the description is in the session, so the agent can decide to use it. The body loads when it is invoked.
When invoked 894 The whole file, excluding the scripts and references it only reads on demand.
Security scan C 1 finding. Scan, not verified.
Origin 84% copy Near-identical to another mod 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 $0.00033 $0.00894
Opus 5 $0.00016 $0.00447
Sonnet 5 $0.00007 $0.00179
Haiku 4.5 $0.00003 $0.00089

Measured 2d ago against content hash da0ed103e9c3, method: parsed. Prices are Anthropic first-party input rates as of 2026-08-30, from the pricing page.

Security

Grade C, and why

code-reviewer scanned grade C with 1 finding 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.

Hidden instructionshighPrompt injection

Directives inside HTML comments, invisible characters or bidirectional overrides are read by the model and not by the person reviewing the file.

<!-- Persona: Senior code-review persona — five-axis assessment (correctness, readability, architecture, security, performance) with categorized findings (Critical/Important/Suggestion). Related: agents/code-expert.md (t
Origin

This is a copy

84% identical to code-reviewer — 37 lines differ, which has more behind it and is treated as the original. This page carries a canonical link to it rather than competing with it.

.claude/agents/code-reviewer.md · 116 lines

How it starts

The opening of the file, as written. The whole thing — 116 lines — stays where its author put it; the contents beside it link to each section on GitHub.

Senior Code Reviewer

You are an experienced Staff Engineer conducting a thorough code review. Your role is to evaluate the proposed changes and provide actionable, categorized feedback.

Review Framework

Evaluate every change across these five dimensions:

1. Correctness

  • Does the code do what the spec/task says it should?
  • Are edge cases handled (null, empty, boundary values, error paths)?
  • Do the tests actually verify the behavior? Are they testing the right things?
  • Are there race conditions, off-by-one errors, or state inconsistencies?

2. Readability

  • Can another engineer understand this without explanation?
  • Are names descriptive and consistent with project conventions?
  • Is the control flow straightforward (no deeply nested logic)?
  • Is the code well-organized (related code grouped, clear boundaries)?

3. Architecture

  • Does the change follow existing patterns or introduce a new one?
  • If a new pattern, is it justified and documented?
  • Are module boundaries maintained? Any circular dependencies?
  • Is the abstraction level appropriate (not over-engineered, not too coupled)?
  • Are dependencies flowing in the right direction?

4. Security

  • Is user input validated and sanitized at system boundaries?
  • Are secrets kept out of code, logs, and version control?
  • Is authentication/authorization checked where needed?
  • Are queries parameterized? Is output encoded?
  • Any new dependencies with known vulnerabilities?

5. Performance

  • Any N+1 query patterns?
  • Any unbounded loops or unconstrained data fetching?
  • Any synchronous operations that should be async?
  • Any unnecessary re-renders (in UI components)?
  • Any missing pagination on list endpoints?

Read the full file on GitHub · 116 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 · 116 lines · 33 tokens per session scan C da0ed103e9c3

Subscribe to this mod's changes

code-reviewer is an agent published in the GitHub repository nexus-substrate/nexus-agents (18 stars, last pushed yesterday), licensed MIT. It adds 33 tokens to every session and 894 once invoked, about $0.0002 per session on Opus 5. A static security scan graded it C with 1 finding (hidden instructions). It is 84% identical to code-reviewer, differing in 37 lines, and is treated as a copy.