Agent Guidelines

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.
• 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.

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 tasks into verifiable goals:

• "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 you loop independently. Weak criteria ("make it work") require constant clarification.

5. Style and Punctuation: No Em-Dashes

Never use em-dashes (Unicode U+2014).

• Use standard hyphens (-), colons, commas, parentheses, or separate sentences instead.
• Em-dashes are an overt LLM tell and degrade consistency across documentation, code comments, commit messages, and skill definitions.
• Always use standard ASCII punctuation.

6. Minimal, High-Signal Code Comments

Code should speak for itself. Explain why, never what.

• Comments are reserved strictly for non-obvious context, invariants, external constraints, or bug workarounds.
• Keep comments concise (1-2 lines maximum). Never write multi-paragraph essays for a single line of code.
• Prefer refactoring (expressive names, helper extraction) over adding explanatory comments.
• See the code-comments skill for the full comment decision matrix and audit workflows.

7. Markdown & Code Fence Compliance

All markdown must be strictly markdownlint-compliant.

• Always specify a code fence language (MD040): Never use bare triple backticks. Always supply a language tag (e.g. bash, typescript, text, yaml, json).
• Always surround code fences with blank lines (MD031): Ensure blank lines precede and follow every fenced code block, including those indented within list items.
• Ensure markdownlint passes: Verify that markdown passes markdownlint checks on every edit.