Fitts's Law and pointer acceleration Agent Skill

Use this skill when the question involves cursor speed, pointer acceleration curves, or interaction with input devices that vary in…

Context cost
3.3k tokensestimated from the bundle, loaded when it triggers
Bundle
2 files · 13.1 kBtext throughout, nothing executable
Licence
Apache-2.0the author’s own terms
Last change
—no release on file
Servers it uses
Noneruns standalone

What it does

Use this skill when the question involves cursor speed, pointer acceleration curves, or interaction with input devices that vary in precision (mouse, trackpad, stylus, touchscreen, eye-tracking). Trigger when designing for varied input devices, building drag interactions, designing scrubbers / sliders / handles, or analyzing why a UI feels "fiddly." Sub-aspect of `fitts-law`; read that first if you haven''t already.

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.

design
Filed under

Design & Media

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.md8.6 kB · preview
--- name: fitts-law-pointer-acceleration ---
6# Fitts's Law and pointer acceleration
7
8The mouse and trackpad are not "raw" inputs — operating systems apply *acceleration curves* that translate physical movement into cursor displacement. Fast physical motion produces disproportionately fast cursor motion; slow physical motion produces precise, slow cursor motion. This curve interacts with Fitts's Law in ways that affect how target size and distance are perceived.
9
10## What pointer acceleration does
11
12A non-accelerated cursor maps physical motion to screen motion 1:1. To cross 1000 pixels, the user must move the mouse 1000 mouse-equivalent units. Fast or slow physical motion makes no difference to the resulting distance.
13
14An accelerated cursor varies the multiplier based on physical speed:
15
16- **Slow physical motion → low multiplier** (e.g., 0.5×). Used for precise positioning over small targets.
17- **Fast physical motion → high multiplier** (e.g., 3–8×). Used for crossing large screen distances quickly.
18
19The acceleration curve is what lets a single mouse on a 4K display traverse the full screen without lifting and re-anchoring (a problem 1990s mice without acceleration had).
20
21For Fitts's Law, this means:
22
23- **Distance is partly free.** Long traversals are accelerated, so movement time grows much less than the linear formula predicts.
24- **Target size still matters.** Once the user is *near* the target, they slow down for fine positioning, and target size dominates again.
This is a preview of SKILL.md. Download or install the skill to get the whole thing.
In the file
SKILL.md1,267 words
Files2
LicenceApache-2.0
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.

≈120
always loaded
The name and description, so the model knows the skill exists and when to reach for it.
3,155
on trigger
The instruction body and 1 supporting file, read only when the skill fires.
1.6%
of a 200k window
Ten skills this size would take about 16% of the window before you open a file.
050k100k150k200k context window

3.3k 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

2 files, 13.1 kB on disk. A bundle is text throughout: the instructions the model reads, plus the templates it fills in.

  • SKILL.md8.6 kB
  • references/pointer-mechanics.md4.5 kB
What is not in it

No dependencies and nothing executable: a skill is text the agent reads, so the bundle is 2 files you can review in full before installing. The Apache-2.0 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.

# Fitts's Law and pointer acceleration · 3.3k tokens when loaded · macOS, Linux mkdir -p .claude/skills && t=$(mktemp -d) && curl -fsSL -o "$t/bundle.tar.gz" https://mcprush.com/api/skills/fitts-s-law-and-pointer-acceleration/bundle.tar.gz && tar -xzf "$t/bundle.tar.gz" -C "$t" && [ -d "$t/fitts-s-law-and-pointer-acceleration" ] && { [ ! -e .claude/skills/fitts-s-law-and-pointer-acceleration ] || { mv .claude/skills/fitts-s-law-and-pointer-acceleration "$t/.previous" && echo "Previous copy moved to $t/.previous"; }; } && mv "$t/fitts-s-law-and-pointer-acceleration" .claude/skills/ && echo "Installed .claude/skills/fitts-s-law-and-pointer-acceleration"
On Windows, or any OS with Node 20+
npx mcprush@latest skill add hashgraph-online/fitts-s-law-and-pointer-acceleration

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

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
Referencehashgraph-online/fitts-s-law-and-pointer-acceleration

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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Publisher
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