200-cursor-rules

Guidelines for writing and maintaining Cursor rules, which are project instructions that Cursor applies to selected files or tasks. They cover rule metadata, file references, examples, and maintenance.

In plain words
What is it for?
Use them when creating or updating Cursor rule files, choosing file patterns, documenting required practices, and adding good and bad code examples.
Why use it?
They provide a consistent structure for rules and make those instructions easier to apply and update. They also clarify how rules should point to project files and code examples.

Cursor rule for Cursor

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.

agentmods
npx agentmods add rules/aiurda/devcontext/200-cursor-rules
Clone the repo
git clone --depth 1 https://github.com/aiurda/devcontext

Made for: Cursor.

Per session 374 This file is loaded in full into every session.
When invoked 374 The same file — it is already loaded in full.
Security scan A 0 findings. Scan, not verified.
Origin 100% copy Near-identical to another mod 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 $0.00374 $0.00374
Opus 5 $0.00187 $0.00187
Sonnet 5 $0.00075 $0.00075
Haiku 4.5 $0.00037 $0.00037

Measured yesterday against content hash 22cfe197dd73, method: parsed. Prices are Anthropic first-party input rates as of 2026-08-30, from the pricing page.

Security

Grade A, and why

200-cursor-rules 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 yesterday.

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.

Origin

This is a copy

100% identical to cursor-rules-meta-guide — 11 lines differ, which has more behind it and is treated as the original. This page carries a canonical link to it rather than competing with it.

.cursor/rules/200-cursor-rules.mdc · 60 lines

What it actually says

  • Required Rule Structure:

    ---
    description: Clear, one-line description of what the rule enforces
    globs: path/to/files/*.ext, other/path/**/*
    alwaysApply: boolean
    ---
    
    - **Main Points in Bold**
      - Sub-points with details
      - Examples and explanations
    
  • File References:

  • Code Examples:

    • Use language-specific code blocks
    // ✅ DO: Show good examples
    const goodExample = true;
    
    // ❌ DON'T: Show anti-patterns
    const badExample = false;
    
  • Rule Content Guidelines:

    • Start with high-level overview
    • Include specific, actionable requirements
    • Show examples of correct implementation
    • Reference existing code when possible
    • Keep rules DRY by referencing other rules
  • Rule Maintenance:

    • Update rules when new patterns emerge
    • Add examples from actual codebase
    • Remove outdated patterns
    • Cross-reference related rules
  • Best Practices:

    • Use bullet points for clarity
    • Keep descriptions concise
    • Include both DO and DON'T examples
    • Reference actual code over theoretical examples
    • Use consistent formatting across rules
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. yesterday First seen · 60 lines · 374 tokens per session scan A 22cfe197dd73

Subscribe to this mod's changes

200-cursor-rules is a cursor rule published in the GitHub repository aiurda/devcontext (47 stars, last pushed 1y ago), licensed MIT. It adds 374 tokens to every session, about $0.0019 per session on Opus 5. A static security scan graded it A with 0 findings. It is 100% identical to cursor-rules-meta-guide, differing in 11 lines, and is treated as a copy.