Compound-System Architecture Agent Skill

Fires when a fellow is ready to design how the AI product is actually built — "architect the product", "how do we build the AI system"…

Context cost
10.5k tokensestimated from the bundle, loaded when it triggers
Bundle
13 files · 41.9 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

Fires when a fellow is ready to design how the AI product is actually built — "architect the product", "how do we build the AI system", "design the AI system", "what's the system architecture", "what does the stack look like". Returns a compound-system architecture (input → router → retrieve/reason/act → validate & guardrails → output over a data layer), a 40/20/30/10 effort-allocation plan, and named model-swap points, then kills any monolithic one-big-prompt design.

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.

data science

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.md10.8 kB · preview
--- name: compound-system-architecture type: generator supersedes: none ---
17# Compound-System Architecture
18
19## What it does
20
21Turns "how do we build this?" into a component pipeline, an effort budget, and a set
22of swap points. The fellow describes the product; the skill returns the architecture as
23a compound system of specialised parts over a data layer, allocates build effort across
24Data / Model / Orchestration / Interface, and marks every place a model is called so a
25new model release is a config change, not a rebuild. It forces the design that most AI
26products actually need and refuses the one most fellows reach for: one big prompt.
27
28## The Icarus reframe
29
30An AI product is not a model with a prompt. It is a compound system — input → router →
31(retrieve / reason / act in parallel) → validate & guardrails → output — sitting on a
32data layer, where each part is specialised and separately swappable. The effort split
33is Data 40 / Model 20 / Orchestration 30 / Interface 10, and the number that stops
34fellows cold is that the model is only 20%: the work is the data you ground on and the
35orchestration around the call, not the call. Because the model is one swappable node,
This is a preview of SKILL.md. Download or install the skill to get the whole thing.
In the file
SKILL.md1,851 words
Files13
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.

≈190
always loaded
The name and description, so the model knows the skill exists and when to reach for it.
10,285
on trigger
The instruction body and 12 supporting files, read only when the skill fires.
5.2%
of a 200k window
Ten skills this size would take about 52% of the window before you open a file.
050k100k150k200k context window

10.5k tokens, estimated from the bundle at four bytes to the token, held for the rest of the session once it triggers. Heavy. Teams tend to install this one per project rather than globally, and load it only when the job comes up.

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

13 files, 41.9 kB on disk. A bundle is text throughout: the instructions the model reads, plus the templates it fills in.

  • SKILL.md10.8 kB
  • template.md5.1 kB
  • examples/sample.md6.2 kB
  • tests/RESULTS.md5.2 kB
  • tests/rubric.json1.1 kB
  • tests/adversarial/01.md1.1 kB
  • tests/adversarial/02.md1.7 kB
  • tests/adversarial/03.md1.3 kB
  • tests/golden/01.md1.9 kB
  • tests/golden/02.md2.0 kB
  • tests/golden/03.md1.9 kB
  • tests/golden/04.md1.7 kB
  • tests/golden/05.md1.9 kB
What is not in it

No dependencies and nothing executable: a skill is text the agent reads, so the bundle is 13 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.

# Compound-System Architecture · 10.5k tokens when loaded · macOS, Linux mkdir -p .claude/skills && t=$(mktemp -d) && curl -fsSL -o "$t/bundle.tar.gz" https://mcprush.com/api/skills/compound-system-architecture/bundle.tar.gz && tar -xzf "$t/bundle.tar.gz" -C "$t" && [ -d "$t/compound-system-architecture" ] && { [ ! -e .claude/skills/compound-system-architecture ] || { mv .claude/skills/compound-system-architecture "$t/.previous" && echo "Previous copy moved to $t/.previous"; }; } && mv "$t/compound-system-architecture" .claude/skills/ && echo "Installed .claude/skills/compound-system-architecture"
On Windows, or any OS with Node 20+
npx mcprush@latest skill add the-utopia-studio/compound-system-architecture

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

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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