Selfmade Agent Skill

Build the thing from scratch — implement the core functionality yourself instead of wrapping an existing library, framework, or service…

Context cost
1.2k tokensestimated from the bundle, loaded when it triggers
Bundle
1 file · 4.8 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

Build the thing from scratch — implement the core functionality yourself instead of wrapping an existing library, framework, or service that already does it. If someone says "make vim", you write the editor's core (buffer, modes, keybindings, rendering) yourself, not `import an-editor-lib`. Use whenever the user invokes /selfmade or says "from scratch", "don't use a library for the core", "build it yourself", "no dependencies doing the real work", "roll your own", or "I want it self-made".

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.md4.8 kB · preview
--- name: selfmade ---
6# Selfmade
7
8Build it yourself. The point is that **the core of what the user asked for is implemented by you, from first principles**, not delegated to a library/framework/API that already solves it. "Make vim" → you write the text buffer, the modal input, the command parser, the keybinding engine, the screen rendering — the actual editor — rather than pulling in an existing editor component and configuring it. The learning, the control, and the ownership are the whole reason someone asks for this.
9
10## What "from scratch" means here
11
12- **The core functionality is yours.** The defining behavior of the thing — the part that *is* the thing — must be your own implementation. For an editor: buffer + modes + input + render. For a parser: your own tokenizer/parser, not a parser-generator library. For a game engine: your own loop/collision/render. For a hash: your own construction (only if the user explicitly wants a self-made one — see the safety note).
13- **Reasonable primitives are still allowed** unless the user says *truly* zero-dependency. Writing to the screen, allocating memory, opening a file, basic math — you don't re-implement the OS or the language runtime. The line is: *the interesting part is yours; the plumbing can be standard.* If the user says "absolutely no dependencies at all," honor that and drop to the lowest primitives available.
14- **When unsure where the line is, ask or state your assumption.** "I'll implement the diff algorithm myself but use the standard file I/O — tell me if you want that self-made too."
15
16## How to build it
17
181. **Understand the thing deeply enough to build it.** You can't implement from scratch what you only understand as a black box. Break the target into its real mechanisms (what does vim actually *do* — modes, motions, operators, registers, the buffer model?). Name the core pieces.
192. **Design the architecture yourself.** Decide the data structures and the module boundaries as if the library you'd normally reach for didn't exist. This is where self-made earns its value — you own the design.
203. **Implement the core, piece by piece, for real.** Write actual working code for each mechanism — no stubs, no "and here you'd call a library," no faking the hard part. The hard part is the point. Pair with [[full-implement]] to keep it complete and production-grade rather than a toy.
214. **Test each piece as you go** ([[test]]) — a from-scratch build has no library's test suite behind it, so your own tests are what make it trustworthy.
225. **Match or beat the reference where it matters.** Self-made isn't an excuse for worse — aim for the real behavior, real edge cases, real performance where it counts.
23
24## What NOT to do
This is a preview of SKILL.md. Download or install the skill to get the whole thing.
In the file
SKILL.md791 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.

≈170
always loaded
The name and description, so the model knows the skill exists and when to reach for it.
1,030
on trigger
The instruction body, read only when the skill fires.
0.60%
of a 200k window
Ten skills this size would take about 6% of the window before you open a file.
050k100k150k200k context window

1.2k 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, 4.8 kB on disk. A bundle is text throughout: the instructions the model reads, plus the templates it fills in.

  • SKILL.md4.8 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.

# Selfmade · 1.2k tokens when loaded · macOS, Linux mkdir -p .claude/skills && t=$(mktemp -d) && curl -fsSL -o "$t/bundle.tar.gz" https://mcprush.com/api/skills/selfmade/bundle.tar.gz && tar -xzf "$t/bundle.tar.gz" -C "$t" && [ -d "$t/selfmade" ] && { [ ! -e .claude/skills/selfmade ] || { mv .claude/skills/selfmade "$t/.previous" && echo "Previous copy moved to $t/.previous"; }; } && mv "$t/selfmade" .claude/skills/ && echo "Installed .claude/skills/selfmade"
On Windows, or any OS with Node 20+
npx mcprush@latest skill add nexus-organization-infosec/selfmade

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

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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