first-principles

first-principles is a skill for Claude Code, Codex from docxology/codomyrmex. It costs 24 tokens per session (216 once invoked), scanned A, original, MIT.

A method for solving unclear technical problems by separating verified facts and constraints from assumptions and preferences.

In plain words
What is it for?
Use it to define the decision, verify key facts, compare possible designs, record trade-offs, and plan the cheapest useful experiment.
Why use it?
It reduces the risk of choosing a solution because of habit, inherited process, or terminology that does not fit the actual problem.

Skill for Claude CodeCodex

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/docxology/codomyrmex/first-principles
Any agent
npx skills add docxology/codomyrmex --skill first-principles
Clone the repo
git clone --depth 1 https://github.com/docxology/codomyrmex

Made for: Claude Code, Codex.

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/docxology/codomyrmex/first-principles.svg)](https://agentmods.dev/skills/docxology/codomyrmex/first-principles)
Your own site
<a href="https://agentmods.dev/skills/docxology/codomyrmex/first-principles"><img src="https://agentmods.dev/badge/skills/docxology/codomyrmex/first-principles.svg" alt="Measured on agentmods" height="20"></a>
Per session 24 Skills are progressive disclosure: only the name and description are preloaded; the body loads when the skill is used.
When invoked 216 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 $0.00024 $0.00216
Opus 5 $0.00012 $0.00108
Sonnet 5 $0.00005 $0.00043
Haiku 4.5 $0.00002 $0.00022

Measured 4d ago against content hash 064ba1254e8c, 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.

.agents/skills/first-principles/SKILL.md · 18 lines

What it actually says

First-Principles Reasoning

Use this skill when a request is ambiguous, a design has accumulated assumptions, or a proposed fix feels like precedent rather than necessity.

  1. State the desired outcome and the decision that must be made.
  2. Separate observations, requirements, constraints, assumptions, and preferences.
  3. Decompose the system into actors, inputs, transformations, outputs, and failure states.
  4. Identify the smallest facts that would change the decision; verify those facts from the repository, tests, or authoritative sources.
  5. Rebuild the solution from the verified facts. Preserve real constraints, but discard inherited process and terminology that do not serve the outcome.
  6. Record trade-offs, unresolved uncertainty, and the cheapest useful next experiment.

Output a compact decision record with: objective, facts, constraints, assumptions, options considered, chosen design, risks, and verification evidence. Do not present an assumption as a fact.

Files

What ships with it

2 files 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 · 18 lines · 24 tokens per session scan A 064ba1254e8c

Subscribe to this mod's changes

first-principles is a skill published in the GitHub repository docxology/codomyrmex (11 stars, last pushed today), licensed MIT. It adds 24 tokens to every session and 216 once invoked, about $0.0001 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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