think-first-principles

think-first-principles is a command for Claude Code from product-on-purpose/thinking-framework-skills. It costs 36 tokens per session (345 once invoked), scanned A, original, Apache-2.0.

A two-step method for reasoning from basic facts instead of inherited conventions. It breaks a problem down to its fundamentals, then tests which assumptions are necessary and which are merely customary.

In plain words
What is it for?
Use it to create a fundamentals sheet, remove unsupported assumptions, and design an approach from the remaining necessary conditions.
Why use it?
It helps you avoid copying patterns that do not fit the problem and rebuild a solution around what is actually required.

Command for Claude Code

Written for Claude Code: argument-hint in frontmatter.

Part of the thinking-framework-skills plugin — 68 skills, 10 commands, 1 agent shipped together

Good fit Use it to create a fundamentals sheet, remove unsupported assumptions, and design an approach from the remaining necessary conditions.

Compare 6 commands from other repositories ↓
Install with agentmods
npx agentmods add commands/product-on-purpose/thinking-framework-skills/think-first-principles
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.

Clone the repo
git clone --depth 1 https://github.com/product-on-purpose/thinking-framework-skills

Made for: Claude Code.

Or install thinking-framework-skills, the plugin that ships this one along with the rest of its 68 skills, 10 commands, 1 agent.

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 think-first-principles

README.md
[![agentmods](https://agentmods.dev/badge/commands/product-on-purpose/thinking-framework-skills/think-first-principles/github.svg)](https://agentmods.dev/commands/product-on-purpose/thinking-framework-skills/think-first-principles)
Your own site
<a href="https://agentmods.dev/commands/product-on-purpose/thinking-framework-skills/think-first-principles"><img src="https://agentmods.dev/badge/commands/product-on-purpose/thinking-framework-skills/think-first-principles/github.svg" alt="Measured on agentmods" height="20"></a>

Or the 80×15 button, for a site that already has a row of RSS and ATOM ones. Only the verdict fits; the numbers stay here.

agentmods 80×15 button for think-first-principles

Your own site · 80×15
<a href="https://agentmods.dev/commands/product-on-purpose/thinking-framework-skills/think-first-principles"><img src="https://agentmods.dev/badge/commands/product-on-purpose/thinking-framework-skills/think-first-principles.svg" alt="Reviewed on agentmods" width="80" height="20"></a>
Per session 36 Only the description is in the session, so the agent can decide to use it. The body loads when it is invoked.
When invoked 345 The whole file, excluding the scripts and references it only reads on demand.
Security scan A 0 findings. A grade says what 26 rules found in the file — not that it is safe.
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 5.1 $0.00036 $0.00345
Opus 5 $0.00018 $0.00172
Sonnet 5 $0.00007 $0.00069
Haiku 4.5 $0.00004 $0.00034

Measured 9d ago against content hash 0721a1572515, method: parsed. Prices are Anthropic first-party input rates as of 2026-09-09, from the pricing page.

Security

Grade A, and why

think-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 9d 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.

commands/think-first-principles.md · 22 lines

What it actually says

Run the think-first-principles recipe: 2 skills chained in a fixed order, carrying forward only the compressed artifact at each handoff.

The compression is the point. Do not paste a whole artifact into the next step; carry exactly what each handoff names, so the chain stays cheaper and sharper than running the skills back to back.

First-principles thinking is not a separate skill here: its durable moves are decomposition and assumption-stripping, both of which the library already ships. This recipe chains them honestly rather than dressing the pair up as a new method.

Run the steps in order, carrying forward only the compressed artifact between them:

  1. think-abstraction-laddering -> carry the irreducible level (the fundamentals the problem reduces to).
  2. think-assumption-reversal (on those fundamentals) -> carry which baked-in assumptions are necessary vs inherited convention.

Composite artifact: a fundamentals sheet - the irreducible truths that survive, the conventions stripped away, and a reconstruction built up from what is actually necessary. Full prose and rationale: recipes/first-principles.md.

Apply the chain to: $ARGUMENTS

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. 9d ago First seen · 22 lines · 36 tokens per session scan A 0721a1572515

Subscribe to this mod's changes

think-first-principles is a command published in the GitHub repository product-on-purpose/thinking-framework-skills (15 stars, last pushed 23d ago), licensed Apache-2.0. It adds 36 tokens to every session and 345 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.