Karpathy Guidelines (verbatim skill text)

Behavioral guidelines to reduce common LLM coding mistakes, derived from Andrej Karpathy’s observations on LLM coding pitfalls (x.com/karpathy/status/2015883857489522876).

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.

State your assumptions explicitly. If uncertain, ask.
If multiple interpretations exist, present them - don’t pick silently.
If a simpler approach exists, say so. Push back when warranted.
If something is unclear, stop. Name what’s confusing. 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 you write 200 lines and it 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.

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.
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.

“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 with a verify: check per step. Strong success criteria let you loop independently. Weak criteria (“make it work”) require constant clarification.