Maintain Codebase Agent Skill

Audits the codebase for maintainability drift: test gaps, shallow modules, tight coupling, dead weight, doc rot, and code smells.

Context cost
1.8k tokensestimated from the bundle, loaded when it triggers
Bundle
3 files · 7.3 kBtext throughout, nothing executable
Licence
MITthe author’s own terms
Last change
—no release on file
Servers it uses
Noneruns standalone

What it does

Audits the codebase for maintainability drift: test gaps, shallow modules, tight coupling, dead weight, doc rot, and code smells. Files the findings as issues.

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.

developer tools

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.md7.0 kB · preview
--- name: maintain-codebase argument-hint: "optional: the area to audit" disable-model-invocation: true ---
8# Maintain Codebase
9
10This session audits the codebase and files issues. The fixes then flow through the implement skill, like other work. An audit that also attempts its own refactors does both tasks badly.
11
12If the docs/ folder or docs/TRACKER.md is missing, stop. Ask the user to invoke the set-up-for-agents skill.
13
14Audit vocabulary: a **module** is anything with an interface and an implementation — a function, a class, or a package. A module is **deep** when a small interface hides much behavior. A module is **shallow** when the interface is almost as complex as what it hides. The **deletion test** shows shallowness. Imagine that you delete the module. If the complexity disappears, the module was a pass-through. If the complexity appears again across the callers, the module was useful.
15
16## Steps
17
181. **Set the scope before you look.** If the argument gives an area, use that area. If not, give weight to recently changed areas:
19 - Find the time when the last audit filed its findings: the newest issue with the label maintenance in the tracker.
20 - Run git log --since={{that time}} --oneline. If no such issue exists, use a recent slice of history: git log --oneline -200.
21 - Give the attention to the files and areas that occur again and again. Depth pays off where change occurs. Code that nobody touches can stay shallow.
22
23 This step is complete when you told the user the scope.
24
252. **Sweep with parallel sub-agents.** Start one read-only sub-agent for each of the codebase dimensions below, except tracker health. Start all of them in one message. Each brief contains: the scope from step 1, the full audit vocabulary above (a sub-agent can read the repository, but not this skill), and its dimension — for the code smells dimension, the full smell baseline. Each sub-agent returns findings with evidence: file:line, and the observed symptom. The dimensions' file reads stay out of this session's context. This session judges the findings:
26 - **Test gaps** — seams where critical or complex behavior crosses, with no test on them.
This is a preview of SKILL.md. Download or install the skill to get the whole thing.
In the file
SKILL.md1,132 words
Files3
LicenceMIT
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.

≈70
always loaded
The name and description, so the model knows the skill exists and when to reach for it.
1,755
on trigger
The instruction body and 2 supporting files, read only when the skill fires.
0.91%
of a 200k window
Ten skills this size would take about 9% of the window before you open a file.
050k100k150k200k context window

1.8k 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

3 files, 7.3 kB on disk. A bundle is text throughout: the instructions the model reads, plus the templates it fills in.

  • SKILL.md7.0 kB
  • agents/openai.yaml0.2 kB
  • assets/templates/finding-issue.md0.1 kB
What is not in it

No dependencies and nothing executable: a skill is text the agent reads, so the bundle is 3 files you can review in full before installing. The MIT licence 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.

# Maintain Codebase · 1.8k tokens when loaded · macOS, Linux mkdir -p .claude/skills && t=$(mktemp -d) && curl -fsSL -o "$t/bundle.tar.gz" https://mcprush.com/api/skills/maintain-codebase/bundle.tar.gz && tar -xzf "$t/bundle.tar.gz" -C "$t" && [ -d "$t/maintain-codebase" ] && { [ ! -e .claude/skills/maintain-codebase ] || { mv .claude/skills/maintain-codebase "$t/.previous" && echo "Previous copy moved to $t/.previous"; }; } && mv "$t/maintain-codebase" .claude/skills/ && echo "Installed .claude/skills/maintain-codebase"
On Windows, or any OS with Node 20+
npx mcprush@latest skill add builtbystef/maintain-codebase

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/maintain-codebase/ 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/maintain-codebase/bundle.tar.gz && tar -xzf "$t/bundle.tar.gz" -C "$t" && [ -d "$t/maintain-codebase" ] && { [ ! -e ~/.claude/skills/maintain-codebase ] || { mv ~/.claude/skills/maintain-codebase "$t/.previous" && echo "Previous copy moved to $t/.previous"; }; } && mv "$t/maintain-codebase" ~/.claude/skills/ && echo "Installed ~/.claude/skills/maintain-codebase" (macOS, Linux) — or add --global to the npx line. The curl line replaces .claude/skills/maintain-codebase/ 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
Versionnot versioned
Publishedno release date on file
PriceFree
Referencebuiltbystef/maintain-codebase

Versions

Its author publishes no version number, so there is nothing here to pin to: what you install is the folder as it stands today. Instructions change more often than APIs do — a skill can be rewritten entirely without anything it depends on moving.

Pinning

Nothing to pin to: this skill carries no version number of its own. What you install is what the folder holds on the day you install it.

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