first-principles

first-principles is a skill for Claude Code, Codex from ironyjk/strategy-frameworks. It costs 44 tokens per session (1,239 once invoked), scanned A, original, MIT.

A problem-solving approach that breaks an issue into basic facts and rebuilds the answer from them. It questions assumptions instead of accepting customary methods.

In plain words
What is it for?
Use it to examine difficult decisions, challenge assumptions, and find solutions based on fundamental facts.
Why use it?
It helps when accepted practices, fixed costs, or “that’s how it’s always done” may be hiding better options.

Skill for Claude CodeCodex

Part of the strategy-frameworks plugin — 27 skills shipped together

Install

Getting it into your agent

One page per mod, every tool's command on it. A separate URL per tool would split the same page into five that compete with each other.

agentmods
npx agentmods add skills/ironyjk/strategy-frameworks/first-principles
Any agent
npx skills add ironyjk/strategy-frameworks --skill first-principles
Clone the repo
git clone --depth 1 https://github.com/ironyjk/strategy-frameworks

Made for: Claude Code, Codex.

Or install strategy-frameworks, the plugin that ships this one along with the rest of its 27 skills.

Wrote this? Show the measurements

A badge with what this costs and how it scanned, read live from this page, so it follows the numbers instead of freezing them. Markdown for a README, HTML for a documentation site or a project page.

agentmods badge for first-principles

README.md
[![agentmods](https://agentmods.dev/badge/skills/ironyjk/strategy-frameworks/first-principles.svg)](https://agentmods.dev/skills/ironyjk/strategy-frameworks/first-principles)
Your own site
<a href="https://agentmods.dev/skills/ironyjk/strategy-frameworks/first-principles"><img src="https://agentmods.dev/badge/skills/ironyjk/strategy-frameworks/first-principles.svg" alt="Measured on agentmods" height="20"></a>
Per session 44 Skills are progressive disclosure: only the name and description are preloaded; the body loads when the skill is used.
When invoked 1,239 The whole file, excluding the scripts and references it only reads on demand.
Security scan A 0 findings. Scan, not verified.
Origin original No closer match found in the catalogue.
Token cost

What it costs to keep this loaded

Counted locally with the o200k_base tokenizer, which is exact for GPT models; Claude uses its own tokenizer and its counts differ. Treat this as one consistent yardstick across the catalogue rather than a bill. Prices are per million input tokens.

ModelPer sessionOnce invoked
Fable 5 $0.00044 $0.01239
Opus 5 $0.00022 $0.00620
Sonnet 5 $0.00009 $0.00248
Haiku 4.5 $0.00004 $0.00124

Measured 4d ago against content hash 20412882c88d, method: parsed. Prices are Anthropic first-party input rates as of 2026-08-30, from the pricing page.

Security

Grade A, and why

first-principles scanned grade A with 0 findings against 26 rules in 11 categories — prompt injection, anti-refusal, data exfiltration, privilege escalation, supply chain, agent snooping, system-prompt leakage, SSRF and excessive agency — measured 4d ago.

A static scan of the body, not an audit. Every finding is printed with the line that produced it so you can judge whether it matters here. A mod is markdown that instructs an agent; that is exactly why what it instructs is worth reading.

Nothing flagged

None of the 26 patterns this scan looks for appear in this file: no shell pipes, no recursive deletes, no credential paths, no hidden text, no instruction-override or anti-refusal phrasing, no agent-config snooping. That is not a guarantee, it is the absence of the things that are checkable.

first-principles/SKILL.md · 117 lines

How it starts

The opening of the file, as written. The whole thing — 117 lines — stays where its author put it; the contents beside it link to each section on GitHub.

First Principles Thinking — Reason from the Ground Up

You are a first principles thinking coach. Help users strip away assumptions and rebuild from fundamental truths.

Historical Lineage

Aristotle (384-322 BC): The Origin

Aristotle defined first principles (archai) as "the first basis from which a thing is known." In his Posterior Analytics, he argued that all knowledge is built on a chain of reasoning that must ultimately rest on self-evident truths — axioms that cannot be deduced from anything more fundamental.

Descartes (1637): Methodic Doubt

In Discourse on the Method, Descartes took first principles further with radical systematic doubt: "I will doubt everything until I find something indubitable."

Descartes' 4 Rules:

  1. Accept nothing as true that you do not clearly know to be true — avoid haste and prejudice
  2. Divide problems into as many parts as necessary to solve them
  3. Think in order — begin with the simplest objects and ascend gradually to the most complex
  4. Review thoroughly — make enumerations so complete that nothing is omitted

His conclusion: "Cogito, ergo sum" (I think, therefore I am) — the one thing he could not doubt.

Feynman: The Anti-Fooling Principle

Richard Feynman brought first principles into modern science with his famous warning:

"The first principle is that you must not fool yourself — and you are the easiest person to fool."

Feynman insisted on deriving results from scratch rather than trusting textbooks, and on testing every claim against experimental evidence.

Musk: Applied First Principles at Scale

Elon Musk became the most visible modern practitioner:

  • Rockets: "Why are rockets so expensive?" Break down to materials — aluminum, titanium, carbon fiber. Raw material cost is ~2% of rocket price. Gap = manufacturing/process opportunity. Result: SpaceX reduced launch costs by 10x.
  • Batteries: Battery packs at $600/kWh. Raw materials (cobalt, nickel, lithium, carbon, aluminum, steel, polymers) at commodity exchange prices = $80/kWh. Gap = opportunity. Result: Tesla drove battery costs down dramatically.
  • Tunneling: "Why is tunneling so expensive?" Break down: the machine is idle 85% of the time. The tunnel is 2x wider than needed. Result: The Boring Company redesigned the process.

Read the full file on GitHub · 117 lines

Files

What ships with it

1 file beside SKILL.md in the same directory: the scripts, references and assets a skill reads on demand. Not counted in the per-session cost; read them before you install if any of them is executable.

Changes

What this file has done since we first saw it

Hashed on every crawl. A supply-chain change to an agent config is a question of when, not whether, so the history is kept rather than the latest state alone.

  1. 4d ago First seen · 117 lines · 44 tokens per session scan A 20412882c88d

Subscribe to this mod's changes

first-principles is a skill published in the GitHub repository ironyjk/strategy-frameworks (11 stars, last pushed 4mo ago), licensed MIT. It adds 44 tokens to every session and 1,239 once invoked, about $0.0002 per session on Opus 5. A static security scan graded it A with 0 findings. No closer match exists in the catalogue, so it is treated as the original; first seen 2026-08-30.

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