Writing code comments Agent Skill

Gates whether a code comment should exist and forces the ones that stay to explain why, not what.

Context cost
1.6k tokensestimated from the bundle, loaded when it triggers
Bundle
1 file · 6.3 kBtext throughout, nothing executable
Licence
not declarednone named by its author
Last change
—no release on file
Servers it uses
Noneruns standalone

What it does

Gates whether a code comment should exist and forces the ones that stay to explain why, not what. Use ALWAYS before writing or editing a comment in any language (Python, TypeScript, Go, Rust, SQL), and when reviewing a diff that adds comments. Removes the comment types that clutter the codebase: narration that restates the code, change-history and chat-context notes ("previously did X", "per PR #123", "AI:"), perishable measurements and current-state stamps ("~20 min build", "currently", "today"), commented-out code, and redundant docstrings.

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.

documentationwriting

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.md6.3 kB · preview
--- name: writing-code-comments ---
11# Writing code comments
12
13Run this before adding or editing any comment. The default is no comment. Good code with clear names carries most of its meaning on its own; a comment earns its place only when it tells a reader something the code cannot.
14
15## The gate: one question
16
17Before writing a comment, answer:
18
19> **What does this tell a future reader that the code itself doesn't?**
20
21If the answer is "it restates what the code does", delete it. Rename the variable or extract a function instead.
22
23A comment worth keeping answers a _why_ the code can't:
24
25- ✅ # ATOMIC_REQUESTS is off, so wrap the two writes that must commit together
26- ✅ // Stripe sends the amount in cents; the rest of our system uses dollars
27- ✅ # Kept in sync with the enum in migrations/0042; update both
28
29## Delete these
This is a preview of SKILL.md. Download or install the skill to get the whole thing.
In the file
SKILL.md1,070 words
Files1
Licencenot declared
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.

≈210
always loaded
The name and description, so the model knows the skill exists and when to reach for it.
1,365
on trigger
The instruction body, read only when the skill fires.
0.79%
of a 200k window
Ten skills this size would take about 8% of the window before you open a file.
050k100k150k200k context window

1.6k 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

1 file, 6.3 kB on disk. A bundle is text throughout: the instructions the model reads, plus the templates it fills in.

  • SKILL.md6.3 kB
What is not in it

No dependencies and nothing executable: a skill is text the agent reads, so the bundle is 1 file you can review in full before installing.

Install

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

# Writing code comments · 1.6k tokens when loaded · macOS, Linux mkdir -p .claude/skills && t=$(mktemp -d) && curl -fsSL -o "$t/bundle.tar.gz" https://mcprush.com/api/skills/writing-code-comments/bundle.tar.gz && tar -xzf "$t/bundle.tar.gz" -C "$t" && [ -d "$t/writing-code-comments" ] && { [ ! -e .claude/skills/writing-code-comments ] || { mv .claude/skills/writing-code-comments "$t/.previous" && echo "Previous copy moved to $t/.previous"; }; } && mv "$t/writing-code-comments" .claude/skills/ && echo "Installed .claude/skills/writing-code-comments"
On Windows, or any OS with Node 20+
npx mcprush@latest skill add karanmrn/writing-code-comments

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/writing-code-comments/ 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/writing-code-comments/bundle.tar.gz && tar -xzf "$t/bundle.tar.gz" -C "$t" && [ -d "$t/writing-code-comments" ] && { [ ! -e ~/.claude/skills/writing-code-comments ] || { mv ~/.claude/skills/writing-code-comments "$t/.previous" && echo "Previous copy moved to $t/.previous"; }; } && mv "$t/writing-code-comments" ~/.claude/skills/ && echo "Installed ~/.claude/skills/writing-code-comments" (macOS, Linux) — or add --global to the npx line. The curl line replaces .claude/skills/writing-code-comments/ 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
Referencekaranmrn/writing-code-comments

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.

Reviews

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