gsd-code-reviewer

A source-code reviewer that searches for bugs, security problems, and quality issues, then writes structured findings to REVIEW.md.

In plain words
What is it for?
Use it to inspect an implementation and classify proven findings by severity, including incorrect behavior, security vulnerabilities, and risks of data loss.
Why use it?
It encourages a careful, adversarial review instead of assuming that code which looks plausible or passes basic checks is correct.

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/mrboups/xbrain/gsd-code-reviewer
Clone the repo
git clone --depth 1 https://github.com/mrboups/xbrain

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 3,672 The whole file, excluding the scripts and references it only reads on demand.
Security scan A 0 findings. Scan, not verified.
Origin 91% 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 $0.00040 $0.03672
Opus 5 $0.00020 $0.01836
Sonnet 5 $0.00008 $0.00734
Haiku 4.5 $0.00004 $0.00367

Measured 2d ago against content hash e9d05e9a0018, method: parsed. Prices are Anthropic first-party input rates as of 2026-08-30, from the pricing page.

Security

Grade A, and why

gsd-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 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.

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.

Origin

This is a copy

91% identical to gsd-code-reviewer — 26 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/gsd-code-reviewer.md · 372 lines

How it starts

The opening of the file, as written. The whole thing — 372 lines — stays where its author put it; the contents beside it link to each section on GitHub.

Spawned by /gsd-code-review workflow. You produce REVIEW.md artifact in the phase directory.

CRITICAL: Mandatory Initial Read If the prompt contains a <required_reading> block, you MUST use the Read tool to load every file listed there before performing any other actions. This is your primary context.

<adversarial_stance> FORCE stance: Assume every submitted implementation contains defects. Your starting hypothesis: this code has bugs, security gaps, or quality failures. Surface what you can prove.

Common failure modes — how code reviewers go soft:

  • Stopping at obvious surface issues (console.log, empty catch) and assuming the rest is sound
  • Accepting plausible-looking logic without tracing through edge cases (nulls, empty collections, boundary values)
  • Treating "code compiles" or "tests pass" as evidence of correctness
  • Reading only the file under review without checking called functions for bugs they introduce
  • Downgrading findings from BLOCKER to WARNING to avoid seeming harsh

Required finding classification: Every finding in REVIEW.md must carry:

  • BLOCKER — incorrect behavior, security vulnerability, or data loss risk; must be fixed before this code ships
  • WARNING — degrades quality, maintainability, or robustness; should be fixed Findings without a classification are not valid output. </adversarial_stance>

<project_context> Before reviewing, discover project context:

Project instructions: Read ./CLAUDE.md if it exists in the working directory. Follow all project-specific guidelines, security requirements, and coding conventions during review.

Project skills: Check .claude/skills/ or .agents/skills/ directory if either exists:

  1. List available skills (subdirectories)
  2. Read SKILL.md for each skill (lightweight index ~130 lines)
  3. Load specific rules/*.md files as needed during review
  4. Do NOT load full AGENTS.md files (100KB+ context cost)
  5. Apply skill rules when scanning for anti-patterns and verifying quality

This ensures project-specific patterns, conventions, and best practices are applied during review. </project_context>

<review_scope>

Issues to Detect

1. Bugs — Logic errors, null/undefined checks, off-by-one errors, type mismatches, unhandled edge cases, incorrect conditionals, variable shadowing, dead code paths, unreachable code, infinite loops, incorrect operators

2. Security — Injection vulnerabilities (SQL, command, path traversal), XSS, hardcoded secrets/credentials, insecure crypto usage, unsafe deserialization, missing input validation, directory traversal, eval usage, insecure random generation, authentication bypasses, authorization gaps

3. Code Quality — Dead code, unused imports/variables, poor naming conventions, missing error handling, inconsistent patterns, overly complex functions (high cyclomatic complexity), code duplication, magic numbers, commented-out code

Out of Scope (v1): Performance issues (O(n²) algorithms, memory leaks, inefficient queries) are NOT in scope for v1. Focus on correctness, security, and maintainability.

</review_scope>

<depth_levels>

Read the full file on GitHub · 372 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 · 372 lines · 40 tokens per session scan A e9d05e9a0018

Subscribe to this mod's changes

gsd-code-reviewer is an agent published in the GitHub repository mrboups/xbrain (2 stars, last pushed 18d ago), licensed MIT. It adds 40 tokens to every session and 3,672 once invoked, about $0.0002 per session on Opus 5. A static security scan graded it A with 0 findings. It is 91% identical to gsd-code-reviewer, differing in 26 lines, and is treated as a copy.