Karpathy Principles

Karpathy Principles is a skill for Claude Code, Codex from GuitarAlchemist/ga. It costs 27 tokens per session (479 once invoked), scanned A, original, MIT.

A set of coding guidelines based on Andrej Karpathy's approach: think through uncertainty, keep solutions simple and make only the changes required.

In plain words
What is it for?
Use it when implementing or reviewing a change that should stay focused, small and consistent with the existing codebase.
Why use it?
It reduces overcomplicated code, speculative features and unrelated edits while making assumptions and trade-offs visible.

Skill for Claude CodeCodex

Written for no agent in particular: nothing here depends on one.

Good fit Use it when implementing or reviewing a change that should stay focused, small and consistent with the existing codebase.

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Install with agentmods
npx agentmods add skills/guitaralchemist/ga/karpathy-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.

Any agent
npx skills add GuitarAlchemist/ga --skill karpathy-principles
Clone the repo
git clone --depth 1 https://github.com/GuitarAlchemist/ga

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 Karpathy Principles

README.md
[![agentmods](https://agentmods.dev/badge/skills/guitaralchemist/ga/karpathy-principles/github.svg)](https://agentmods.dev/skills/guitaralchemist/ga/karpathy-principles)
Your own site
<a href="https://agentmods.dev/skills/guitaralchemist/ga/karpathy-principles"><img src="https://agentmods.dev/badge/skills/guitaralchemist/ga/karpathy-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 Karpathy Principles

Your own site · 80×15
<a href="https://agentmods.dev/skills/guitaralchemist/ga/karpathy-principles"><img src="https://agentmods.dev/badge/skills/guitaralchemist/ga/karpathy-principles.svg" alt="Reviewed on agentmods" width="80" height="20"></a>
Per session 27 Skills are progressive disclosure: only the name and description are preloaded; the body loads when the skill is used.
When invoked 479 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 $0.00027 $0.00479
Opus 5 $0.00014 $0.00239
Sonnet 5 $0.00005 $0.00096
Haiku 4.5 $0.00003 $0.00048

Measured 9d ago against content hash 9167c263334f, method: parsed. Prices are Anthropic first-party input rates as of 2026-09-09, from the pricing page.

Security

Grade A, and why

Karpathy 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.

.agent/skills/karpathy-principles/SKILL.md · 51 lines

What it actually says

Karpathy-Inspired Coding Guidelines

When this skill is active, strictly adhere to the following four principles.

1. Think Before Coding

Don't assume. Don't hide confusion. Surface tradeoffs.

  • State assumptions explicitly: If uncertain, ask rather than guess.
  • Present multiple interpretations: Don't pick silently when ambiguity exists.
  • Push back when warranted: If a simpler approach exists, say so.
  • Stop when confused: Name what's unclear and ask for clarification.

2. Simplicity First

Minimum code that solves the problem. Nothing speculative.

  • No features beyond what was asked.
  • No abstractions for single-use code.
  • No "flexibility" or "configurability" that wasn't requested.
  • No error handling for impossible scenarios.
  • If 200 lines could be 50, rewrite it.
  • The Test: Would a senior engineer say this is overcomplicated? If yes, simplify.

3. Surgical Changes

Touch only what you must. Clean up only your own mess.

  • Don't "improve" adjacent code, comments, or formatting.
  • Don't refactor things that aren't broken.
  • Match existing style, even if you'd do it differently.
  • If you notice unrelated dead code, mention it — don't delete it.
  • Orphans: Remove imports/variables/functions that YOUR changes made unused. Don't remove pre-existing dead code unless asked.
  • The Test: Every changed line should trace directly to the user's request.

4. Goal-Driven Execution

Define success criteria. Loop until verified.

Transform imperative tasks into verifiable goals.

  • Instead of "Add validation", use "Write tests for invalid inputs, then make them pass".
  • Instead of "Fix the bug", use "Write a test that reproduces it, then make it pass".
  • Instead of "Refactor X", use "Ensure tests pass before and after".

For multi-step tasks, state a brief plan:

  1. [Step] → verify: [check]
  2. [Step] → verify: [check]
  3. [Step] → verify: [check]
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 · 51 lines · 27 tokens per session scan A 9167c263334f

Subscribe to this mod's changes

Karpathy Principles is a skill published in the GitHub repository GuitarAlchemist/ga (2 stars, last pushed yesterday), licensed MIT. It adds 27 tokens to every session and 479 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 2026-08-31.