Explain Diff Agent Skill

Use when the user asks for a rich explanation of a code change, diff, branch, or PR.

Context cost
825 tokensestimated from the bundle, loaded when it triggers
Bundle
1 file · 3.3 kBtext throughout, nothing executable
Licence
MITthe author’s own terms
Last change
—no release on file
Servers it uses
Noneruns standalone

What it does

Use when the user asks for a rich explanation of a code change, diff, branch, or PR. Produces HTML output.

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.

documentation

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.md3.3 kB · preview
--- name: explain-diff-html ---
6# Explain Diff
7
8Please make me a rich, interactive explanation of the specified code change.
9
10It should have these sections:
11
12- Background: Explain the existing system relevant to this change. (You should broadly explore surrounding code for this.) We don't know how much the reader already knows, so include a deep background for beginners (note that it can be skipped if the reader is already familiar), and then a more narrow background directly relevant to the change.
13- Intuition: Explain the core intuition for the code change. The focus here is to explain the essence, not the full details. Use concrete examples with toy data. Use figures and diagrams liberally.
14- Code: Do a high-level walkthrough of the changes to the code. Group/order the changes in an understandable way.
15- Quiz: Come up with five questions that test the reader's knowledge of this PR. This should be medium difficulty, difficult enough that you actually need to understand the substance of the PR to answer them, but not gotchas. The goal is to help the reader make sure that they've actually understood. These should be presented as interactive multiple-choice questions, and when the user clicks, it tells them whether they were correct and gives feedback.
16 Write options so the correct answer is not obvious from length or phrasing alone (keep options roughly comparable; avoid padding the right one). Shuffle option order programmatically with a deterministic seed (e.g. question index), not by hand-picking positions when writing the quiz.
17
18Format:
19
20- Output a single self-contained HTML file which includes CSS and JavaScript. Make the whole thing one long page with section headers and a table of contents. Don't use tabs for the top-level structure. Basic responsive styling so you can view it on a phone is nice too. Put the file in a global place on my computer outside of the code repo, and make sure the filename always starts with today's date in YYYY-MM-DD- format, because it helps keep the files time-sorted and out of version control. For example: /tmp/2026-01-12-explanation-<slug>.html
21- Please write with the clarity and flow of Martin Kleppmann, making it engaging and written in classic style. Transitions between sections should be smooth.
22- Some tips on diagrams. Ideally, you should pick a small number of diagram families that can be reused throughout the explanation to explain various cases. Some useful kinds of diagrams:
23 - A very simplified version of the UI that the user sees in the app, to explain UI changes.
24 - A system diagram showing data flow or communication between components. Make sure to include example data here!
This is a preview of SKILL.md. Download or install the skill to get the whole thing.
In the file
SKILL.md544 words
Files1
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.

≈40
always loaded
The name and description, so the model knows the skill exists and when to reach for it.
785
on trigger
The instruction body, read only when the skill fires.
0.41%
of a 200k window
Ten skills this size would take about 4% of the window before you open a file.
050k100k150k200k context window

825 tokens, estimated from the bundle at four bytes to the token, held for the rest of the session once it triggers. Small enough to keep loaded permanently without thinking about it.

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

  • SKILL.md3.3 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. 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.

# Explain Diff · 825 tokens when loaded · macOS, Linux mkdir -p .claude/skills && t=$(mktemp -d) && curl -fsSL -o "$t/bundle.tar.gz" https://mcprush.com/api/skills/explain-diff/bundle.tar.gz && tar -xzf "$t/bundle.tar.gz" -C "$t" && [ -d "$t/explain-diff" ] && { [ ! -e .claude/skills/explain-diff ] || { mv .claude/skills/explain-diff "$t/.previous" && echo "Previous copy moved to $t/.previous"; }; } && mv "$t/explain-diff" .claude/skills/ && echo "Installed .claude/skills/explain-diff"
On Windows, or any OS with Node 20+
npx mcprush@latest skill add baranbingol1/explain-diff

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/explain-diff/ 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/explain-diff/bundle.tar.gz && tar -xzf "$t/bundle.tar.gz" -C "$t" && [ -d "$t/explain-diff" ] && { [ ! -e ~/.claude/skills/explain-diff ] || { mv ~/.claude/skills/explain-diff "$t/.previous" && echo "Previous copy moved to $t/.previous"; }; } && mv "$t/explain-diff" ~/.claude/skills/ && echo "Installed ~/.claude/skills/explain-diff" (macOS, Linux) — or add --global to the npx line. The curl line replaces .claude/skills/explain-diff/ 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. It appears as explain-diff-html in Gemini CLI, Codex, Copilot and Grok (its own name); Claude Code lists it by the folder name, explain-diff.

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
Referencebaranbingol1/explain-diff

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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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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