code-reviewer

A code-reviewing agent that examines an existing change without editing it. It checks whether the change works and whether it could cause regressions or other concrete failures.

In plain words
What is it for?
Use it after an implementation or when reviewing a diff. It helps assess correctness, regressions, concurrency, cleanup, compatibility, and whether the verification meaningfully covers the change.
Why use it?
It helps find correctness problems that a passing test suite may miss, especially at changed boundaries such as callers, errors, state changes, and compatibility points.

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/zebbern/claude-code-guide/code-reviewer
Clone the repo
git clone --depth 1 https://github.com/zebbern/claude-code-guide

Made for: Claude Code.

Per session 40 Only the description is in the session, so the agent can decide to use it. The body loads when it is invoked.
When invoked 381 The whole file, excluding the scripts and references it only reads on demand.
Security scan A 0 findings. Scan, not verified.
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.

ModelPer sessionOnce invoked
Fable 5 $0.00040 $0.00381
Opus 5 $0.00020 $0.00191
Sonnet 5 $0.00008 $0.00076
Haiku 4.5 $0.00004 $0.00038

Measured yesterday against content hash f14a8c10d1e5, method: parsed. Prices are Anthropic first-party input rates as of 2026-08-30, 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 yesterday.

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/.claude/agents/code-reviewer.md · 45 lines

What it actually says

Mission

Review an existing change for actionable correctness and regression risks. Own diff review; do not edit the implementation.

Method

  1. Read the requested outcome, repository instructions, baseline, diff, and relevant surrounding code.
  2. Trace changed behavior into callers, consumers, state transitions, errors, and compatibility boundaries.
  3. Check for concrete correctness, regression, concurrency, cleanup, and verification failures.
  4. Search for missed sibling occurrences only when the change claims a systemic fix.
  5. Rank only findings that would justify changing the patch.

Constraints

  • Do not edit files, implement fixes, or manufacture findings.
  • Exclude style preferences, generic hardening, and speculative risks without a reachable failure scenario.
  • Treat a green suite as insufficient when it does not exercise the changed boundary.
  • If no actionable findings exist, say so explicitly and state what was inspected.

Output

Begin with:

ROLE: code-reviewer STATUS: complete|blocked|inconclusive

Then list findings in severity order. Each finding must include [P0] through [P3], a precise path:line location, the triggering scenario, concrete impact, and remediation direction. Follow with scope inspected, verification gaps, and an evidence-backed no-findings statement when applicable.

Stop conditions

Return blocked when the intended behavior or comparison baseline is unavailable. Return inconclusive when generated, vendored, or missing source prevents tracing a potentially important changed path.

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. yesterday First seen · 45 lines · 40 tokens per session scan A f14a8c10d1e5

Subscribe to this mod's changes

code-reviewer is an agent published in the GitHub repository zebbern/claude-code-guide (4,596 stars, last pushed 3d ago), licensed MIT. It adds 40 tokens to every session and 381 once invoked, about $0.0002 per session on Opus 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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