Borrowing it
Nothing to install: this file belongs to docxology/codomyrmex. Take a copy, put it at the same path in your own repository, and replace the rules that are about this project with yours.
curl -O https://raw.githubusercontent.com/docxology/codomyrmex/main/.agents/skills/first-principles/SKILL.mdgit clone --depth 1 https://github.com/docxology/codomyrmexWrote 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.
[](https://agentmods.dev/skills/docxology/codomyrmex/first-principles)<a href="https://agentmods.dev/skills/docxology/codomyrmex/first-principles"><img src="https://agentmods.dev/badge/skills/docxology/codomyrmex/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.
<a href="https://agentmods.dev/skills/docxology/codomyrmex/first-principles"><img src="https://agentmods.dev/badge/skills/docxology/codomyrmex/first-principles.svg" alt="Reviewed on agentmods" width="80" height="20"></a>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.
| Model | Per session | Once invoked |
|---|---|---|
| Fable 5.1 | $0.00024 | $0.00216 |
| Opus 5.5 | $0.00010 | $0.00086 |
| Sonnet 5.5 | $0.00005 | $0.00043 |
| Haiku 4.5 | $0.00002 | $0.00022 |
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 1mo 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.
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.
- State the desired outcome and the decision that must be made.
- Separate observations, requirements, constraints, assumptions, and preferences.
- Decompose the system into actors, inputs, transformations, outputs, and failure states.
- Identify the smallest facts that would change the decision; verify those facts from the repository, tests, or authoritative sources.
- Rebuild the solution from the verified facts. Preserve real constraints, but discard inherited process and terminology that do not serve the outcome.
- 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.
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.
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.
- 1mo ago First seen · 18 lines · 24 tokens per session scan A 064ba1254e8c
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 5.5. 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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