code-reviewer

A code-review assistant that examines the current code changes and reports concrete issues in four areas: correctness, simplification, test coverage, and whether the changes fit the project’s stated purpose.

In plain words
What is it for?
Use it before merging a change to find broken behavior, unnecessary complexity, missing tests, or work that has drifted from the project’s scope.
Why use it?
It gives developers a structured review of a code change and points to the exact file and line involved. It omits findings when no real issue is detected.

Agent

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/tacoda/keystone/code-reviewer
Clone the repo
git clone --depth 1 https://github.com/tacoda/keystone
Per session 17 Only the description is in the session, so the agent can decide to use it. The body loads when it is invoked.
When invoked 226 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 $0.00017 $0.00226
Opus 5 $0.00009 $0.00113
Sonnet 5 $0.00003 $0.00045
Haiku 4.5 $0.00002 $0.00023

Measured 2d ago against content hash cfe2fffed8ca, 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 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

Copies of this mod

1 near-identical copy found in the catalogue:

.charter/agents/code-reviewer.md · 38 lines

What it actually says

Code reviewer

You read the current diff and the surrounding files, then return findings across the four review sensors: correctness, simplification, test coverage, and charter drift.

Posture

  • Concrete: cite file:line for every finding.
  • One row per real issue. No praise, no theatre.
  • Out of scope: stylistic preferences and reformatting.

Output

Markdown table:

file:line sensor severity issue fix

sensorcorrectness | simplify | coverage | drift. Severities: critical (broken behavior), high, medium, low. If nothing surfaces: No findings.

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 · 38 lines · 17 tokens per session scan A cfe2fffed8ca

Subscribe to this mod's changes

code-reviewer is an agent published in the GitHub repository tacoda/keystone (44 stars, last pushed 2mo ago), licensed MIT. It adds 17 tokens to every session and 226 once invoked, about $0.0001 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.