andrej-karpathy-skill

andrej-karpathy-skill is a skill for Claude Code, Codex from duolahypercho/andrej-karpathy-skills. It costs 51 tokens per session (650 once invoked), scanned A, original, MIT.

A set of coding-agent guidelines inspired by Andrej Karpathy for thinking carefully before editing code and keeping changes small.

In plain words
What is it for?
Writing, reviewing, debugging, and refactoring code when you want explicit assumptions, simple implementations, surgical edits, and verifiable success criteria.
Why use it?
It helps avoid guessing, overengineering, unrelated edits, and changes that cannot be checked against a clear goal.

Skill for Claude CodeCodex

Written for no agent in particular: nothing here depends on one. Also seen: mentions Codex.

Good fit Writing, reviewing, debugging, and refactoring code when you want explicit assumptions, simple implementations, surgical edits, and verifiable success criteria.

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Install with agentmods
npx agentmods add skills/duolahypercho/andrej-karpathy-skills/andrej-karpathy-skill
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 duolahypercho/andrej-karpathy-skills --skill andrej-karpathy-skill
Clone the repo
git clone --depth 1 https://github.com/duolahypercho/andrej-karpathy-skills

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 andrej-karpathy-skill

README.md
[![agentmods](https://agentmods.dev/badge/skills/duolahypercho/andrej-karpathy-skills/andrej-karpathy-skill/github.svg)](https://agentmods.dev/skills/duolahypercho/andrej-karpathy-skills/andrej-karpathy-skill)
Your own site
<a href="https://agentmods.dev/skills/duolahypercho/andrej-karpathy-skills/andrej-karpathy-skill"><img src="https://agentmods.dev/badge/skills/duolahypercho/andrej-karpathy-skills/andrej-karpathy-skill/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 andrej-karpathy-skill

Your own site · 80×15
<a href="https://agentmods.dev/skills/duolahypercho/andrej-karpathy-skills/andrej-karpathy-skill"><img src="https://agentmods.dev/badge/skills/duolahypercho/andrej-karpathy-skills/andrej-karpathy-skill.svg" alt="Reviewed on agentmods" width="80" height="20"></a>
Per session 51 Skills are progressive disclosure: only the name and description are preloaded; the body loads when the skill is used.
When invoked 650 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 $0.00051 $0.00650
Opus 5 $0.00026 $0.00325
Sonnet 5 $0.00010 $0.00130
Haiku 4.5 $0.00005 $0.00065

Measured 13d ago against content hash 455ce975830d, method: parsed. Prices are Anthropic first-party input rates as of 2026-09-12, from the pricing page.

Security

Grade A, and why

andrej-karpathy-skill 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 13d 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.

skills/andrej-karpathy-skill/SKILL.md · 85 lines

How it starts

The opening of the file, as written. The whole thing — 85 lines — stays where its author put it; the contents beside it link to each section on GitHub.

Andrej Karpathy Skill

Use this skill as a Codex-native version of the Karpathy coding-agent guidelines.

The goal is not to add a new framework. The goal is to make Codex behave more carefully on real code: clarify before guessing, prefer simple implementations, avoid unrelated edits, and verify against a concrete goal.

The Four Checks

1. Think Before Coding

Before editing, make the task explicit.

  • State the interpretation you are using.
  • Surface assumptions that affect the implementation.
  • Name meaningful tradeoffs when more than one path is reasonable.
  • Ask a concise clarifying question when guessing would create real risk.
  • If the task is obvious and low-risk, state the assumption briefly and proceed.

Codex should not silently pick a risky interpretation and run with it.

2. Keep It Simple

Implement the smallest thing that satisfies the current request.

  • Do not add features the user did not ask for.
  • Do not add configurability before there is a real need.
  • Do not create abstractions for one caller.
  • Do not introduce new dependencies for logic the repo can already express simply.
  • If the first approach feels like architecture, look for the direct version first.

Codex should solve today's problem, not design tomorrow's system by accident.

3. Make Surgical Changes

Keep the diff tied to the request.

  • Touch only the files needed for the task.
  • Match the local style even when another style is personally preferable.
  • Do not reformat, rename, or reorganize adjacent code as a side effect.
  • Clean up imports, variables, or helpers made unused by your own change.
  • Mention unrelated dead code or design problems separately instead of fixing them inside the patch.

Codex should leave the surrounding code recognizable.

4. Define The Goal And Verify It

Turn the request into a checkable outcome before calling it done.

  • Bug fix: identify the failing case and the expected behavior.
  • Feature: identify the behavior the user should be able to observe.
  • Refactor: identify the behavior that must remain unchanged.
  • Review: identify concrete risks, missing tests, and regressions.

Read the full file on GitHub · 85 lines

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. 13d ago First seen · 85 lines · 51 tokens per session scan A 455ce975830d

Subscribe to this mod's changes

andrej-karpathy-skill is a skill published in the GitHub repository duolahypercho/andrej-karpathy-skills (231 stars, last pushed 3mo ago), licensed MIT. It adds 51 tokens to every session and 650 once invoked, about $0.0003 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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