Feature Code Reviewer Agent Skill

Use when a change has been written and the user wants it judged before it ships: "review this", "is this code any good", "will this be…

Context cost
3.5k tokensestimated from the bundle, loaded when it triggers
Bundle
11 files · 16.0 kB6 scripts among them — read before you run
Licence
PolyForm Noncommercial License 1.0.0the author’s own terms
Last change
—v1.0
Servers it uses
Noneruns standalone

What it does

Use when a change has been written and the user wants it judged before it ships: "review this", "is this code any good", "will this be maintainable", "clean this up" on a just-built change, "did we do this the right way", or a pointer at a feature folder. Reads the specification and the diff, checks every touched file against clean-code practice and this repo's own conventions, applies internal refactors that leave behavior unchanged, and writes what-was-reviewed.md with a pass or fail verdict. Use even when the user does not say "review" or "code quality".

What this skill changes about the agent has not been set out here as a list. Its SKILL.md, shown below, says it in the author’s own words.

collaboration

The skill itself

A skill is instructions the model reads, so you can see what you are getting: below is the start of its SKILL.md. The front matter loads with every session, the body loads when the skill triggers, and the whole file comes with the install.

SKILL.md7.2 kB · preview
--- name: feature-code-reviewer compatibility: >- Requires git and a shell to resolve the diff. Works in any Agent Skills host. Edits files when applying refactors; does not commit or push unless asked. No network access required. license: PolyForm Noncommercial License 1.0.0 metadata: author: Lucas Winter version: "1.0" family: feature-builder ---
26# feature-code-reviewer
27
28Core job: judge whether this change will still be easy to live with in a year. Be strict. Clean code and this repo's good practice win over "it works."
29
30Input: what-to-build.md, the diff, and nearby existing code.
31
32Output: safe refactors if needed, and what-was-reviewed.md from [assets/what-was-reviewed.md](assets/what-was-reviewed.md).
33
34Run **after** feature-developer and **before** feature-tester. Skip only for a tiny, obvious one-line fix the user already trusts.
35
36## Gotchas
37
38- feature-developer commits on its feature branch, so the diff is git diff <base>...HEAD. what-was-implemented.md names the branch, the base, and the commit. If the user told the developer not to commit, the work sits in the working tree instead: use git diff, git diff --cached, and the untracked files from git status --porcelain. If neither yields files, stop and ask. Never review from the write-up alone.
39- **Write-up root.** <root> is the docs **directory** named on the Feature-folder write-ups line in the repo's AGENTS.md. If that line is missing, use the same line in .cursor/rules/agent-engineer-skills.mdc. If both are missing, <root> is agent-engineer-skills. That path must be a folder. Never create or read a file named aes-write-up-root. The specification lives at <root>/<feature-name>/what-to-build.md. If that tree is missing but docs/features/<feature-name>/ exists, use the old folder. Never create both trees for one name. concept.md is the old filename for the same artifact. Write what-was-reviewed.md next to whichever one you used.
40- A must-fix that cannot be fixed without changing what the user gets is still a fail. Record the finding as blocked-specifier and send them to feature-specifier. Blocked is a property of the finding, not a third verdict.
41- Windows PowerShell 5.1 has no && operator, so joined commands fail there. PowerShell 7 and POSIX shells accept it. When the shell is unknown, run git commands one per call.
42- Refactoring is allowed; redesigning is not. If a fix would change behavior, an interface the specification named, or a wall, it is out of bounds no matter how much better it would be.
43
44## How (mandatory order)
This is a preview of SKILL.md. Download or install the skill to get the whole thing.
In the file
SKILL.md1,123 words
Files11
LicencePolyForm Noncommercial License 1.0.0
Why you can read it

Nothing in a skill executes. The client loads the text and the model follows it, so a skill can be audited the way a runbook is — by reading it.

What it costs in context

Skills are not billed by the call. They are paid for in context: every token the instructions occupy is a token your code, your diff and your conversation cannot use. Here is what this one takes and when it takes it.

≈300
always loaded
The name and description, so the model knows the skill exists and when to reach for it.
3,225
on trigger
The instruction body and 10 supporting files, read only when the skill fires.
1.8%
of a 200k window
Ten skills this size would take about 18% of the window before you open a file.
050k100k150k200k context window

3.5k tokens, estimated from the bundle at four bytes to the token, held for the rest of the session once it triggers. Middling. Fine to keep on in a project where you use it weekly, worth unloading in one where you never do.

Servers bill, skills cost

A server charges by the month. A skill charges once per session, in context, and then keeps charging it for as long as the session lives.

Before and after

The same question, put to the same model twice: once as it comes, and once with these instructions loaded.

No worked example has been published for this skill yet.

The procedure it runs

The procedure has not been set out here step by step. It is in the body of its SKILL.md: the start of it is shown above, and the whole file comes with the install.

Prose, not code

These steps are written for a model to follow, not executed by a runtime. It can still be told to skip one, and it will say so when it does.

Servers it uses

None. This skill calls no MCP servers at all.

Everything it needs is in the instructions, so it works in a project with nothing connected — the model reads the file and changes how it works with what it can already reach.

Its SKILL.md does not declare which tools it asks the agent for, so what it touches is whatever the instructions themselves ask for — read them before you install it.

What it asks for
Writes filesnot declared
Network accessnot declared

This SKILL.md carries no allowed-tools line, so neither is declared. A skill grants no permissions of its own — it can only ask for tools your client already has.

What it will not do

Every skill is narrow, and the useful ones say where they stop. These are the jobs this one is the wrong tool for.

What this skill is not for has not been published here. Nothing is implied by that: it is a section the author has not filled in.

What is in the bundle

11 files, 16.0 kB on disk. Mostly text — the instructions the model reads — with 6 scripts in it that your client would run only if the instructions tell it to.

  • SKILL.md7.2 kB
  • assets/what-was-reviewed.md0.8 kB
  • evals/evals.json4.2 kB
  • evals/files/format-cents-clean/src/index.js0.3 kB
  • evals/files/format-cents-clean/src/money.js0.2 kB
  • evals/files/format-cents-clean/src/orders.js0.5 kB
  • evals/files/format-cents-smelly/src/index.js0.3 kB
  • evals/files/format-cents-smelly/src/money.js0.1 kB
  • evals/files/format-cents-smelly/src/orders.js0.5 kB
  • evals/files/format-cents-clean/agent-engineer-skills/format-cents/what-was-implemented.md1.0 kB
  • evals/files/format-cents-smelly/agent-engineer-skills/format-cents/what-was-implemented.md0.9 kB
What is not in it

A skill installs nothing and depends on nothing: it is a folder your client reads. This one carries 6 scripts beside the text, so the bundle is 11 files you can review in full before installing. The PolyForm Noncommercial License 1.0.0 covers the templates and examples as well as the instructions.

Install

Installing copies the bundle into your project. Nothing runs at install time — the files sit on disk until the model reads them.

# Feature Code Reviewer · 3.5k tokens when loaded · macOS, Linux mkdir -p .claude/skills && t=$(mktemp -d) && curl -fsSL -o "$t/bundle.tar.gz" https://mcprush.com/api/skills/feature-code-reviewer/bundle.tar.gz && tar -xzf "$t/bundle.tar.gz" -C "$t" && [ -d "$t/feature-code-reviewer" ] && { [ ! -e .claude/skills/feature-code-reviewer ] || { mv .claude/skills/feature-code-reviewer "$t/.previous" && echo "Previous copy moved to $t/.previous"; }; } && mv "$t/feature-code-reviewer" .claude/skills/ && echo "Installed .claude/skills/feature-code-reviewer"
On Windows, or any OS with Node 20+
npx mcprush@latest skill add lucas-winter-berlin/feature-code-reviewer

Windows PowerShell says 'running scripts is disabled on this system'? Run Set-ExecutionPolicy -Scope CurrentUser RemoteSigned once, or type npx.cmd instead of npx (codex.cmd, gemini.cmd, grok.cmd likewise). PowerShell 7 needs neither. Writes to .claude/skills/feature-code-reviewer/ in the current project. For every project instead, run mkdir -p ~/.claude/skills && t=$(mktemp -d) && curl -fsSL -o "$t/bundle.tar.gz" https://mcprush.com/api/skills/feature-code-reviewer/bundle.tar.gz && tar -xzf "$t/bundle.tar.gz" -C "$t" && [ -d "$t/feature-code-reviewer" ] && { [ ! -e ~/.claude/skills/feature-code-reviewer ] || { mv ~/.claude/skills/feature-code-reviewer "$t/.previous" && echo "Previous copy moved to $t/.previous"; }; } && mv "$t/feature-code-reviewer" ~/.claude/skills/ && echo "Installed ~/.claude/skills/feature-code-reviewer" (macOS, Linux) — or add --global to the npx line. The curl line replaces .claude/skills/feature-code-reviewer/ only after the download succeeds, so files left there by another skill of the same name, or by an older release, do not mix in. A copy already there is moved aside, not deleted, and the line prints where.

Which clients pick it up on their own

A skill is a folder of text. Most of these read a skills folder and pick it up without being told; the rest take the same folder another way — an upload in the app, a parameter on an API call — and then choose it by its description just the same.

Claude Code.claude/skills/
Claude DesktopCustomize › Skills
ChatGPTSkills › Create › Upload
Cursor.cursor/skills/
VS Code.github/skills/
Codex CLI.agents/skills/
Gemini CLI.gemini/skills/
Grok Build.grok/skills/
Microsoft CopilotSkills › Upload a skill
PerplexityComputer › Skills › Upload a skill
DeepSeek Harness.dsh/skills/
Zed.agents/skills/
Devin Desktop.devin/skills/
Windsurf (legacy).windsurf/skills/
OpenAI Agents SDKInstructions or sandbox Skills
HTTP / APIa request parameter
This release
Version1.0
Publishedno release date on file
PriceFree
Referencelucas-winter-berlin/feature-code-reviewer

Versions

v1.0 is what is on the shelf; no release here carries a date. Instructions change more often than APIs do — a skill can be rewritten entirely without anything it depends on moving.

v1.0
  • No earlier releases have been published to the marketplace.
Pinning

The install command always fetches the release that is current the day you run it — v1.0 today — and cannot ask for an earlier one. The copy on your disk does not change until you run it again.

Reviews

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Anybody with an account, one review each. It carries the version that was current when you wrote it, and the publisher may reply once.

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