| name | karpathy-guidelines |
| description | Use when writing, reviewing, or refactoring code, and the user wants the four principles applied — Think Before Coding, Simplicity First, Surgical Changes, Goal-Driven Execution. Triggers: "follow the four principles", "be surgical", "simplify first", "stop assuming", "write goals not just code", "no drive-by refactors", "this change should be focused". |
Karpathy Guidelines
Behavioral guidelines to reduce common LLM coding mistakes, derived from Andrej Karpathy's observations on LLM coding pitfalls.
Tradeoff: These guidelines bias toward caution over speed. For trivial tasks, use judgment.
1. Think Before Coding
Don't assume. Don't hide confusion. Surface tradeoffs.
Before implementing:
- State your 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. Ask.
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.
Ask yourself: "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.
When editing existing code:
- 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.
When your changes create 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… | Transform to… |
|---|
| "Add validation" | "Write tests for invalid inputs, then make them pass" |
| "Fix the bug" | "Write a test that reproduces it, then make it pass" |
| "Refactor X" | "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]
Strong success criteria let the LLM loop independently. Weak criteria ("make it work") require constant clarification.
How to know it's working
- Fewer unnecessary changes in diffs — only requested changes appear.
- Fewer rewrites due to overcomplication — code is simple the first time.
- Clarifying questions come before implementation — not after mistakes.
- Clean, minimal PRs — no drive-by refactoring or "improvements".
Tradeoff note
These guidelines bias toward caution over speed. For trivial tasks (typo fixes, obvious one-liners), use judgment — not every change needs the full rigor.
The goal is reducing costly mistakes on non-trivial work, not slowing down simple tasks.
Source / license
Adapted from forrestchang/andrej-karpathy-skills, MIT.
