Are You Really Using Cursor AI to Its Full Potential? A Guide to Building Your "Stdlib"

Many developers are diving into AI-assisted coding with tools like Cursor, but are they truly maximizing its capabilities? This article explores how to move beyond basic usage and leverage Cursor's powerful features, particularly Cursor Rules, to create a personalized and highly efficient development workflow.

The Common Pitfalls of Using Cursor AI

During recent discussions with software engineers across various experience levels, a few common mistakes in using Cursor AI have emerged:

• Treating Cursor as a glorified search engine: Simply using it to look up code snippets instead of leveraging its generative capabilities.
• Poorly defined prompts: Failing to provide sufficient context or clear instructions, leading to suboptimal results. Saying just "implement XYZ please" is not sufficient
• Using Cursor as an IDE replacement: Overlooking its potential as an autonomous agent capable of complex, automated tasks.
• Ignoring the power of programmability: Being unaware of how to fine-tune Cursor's behavior and outcomes through rules and configurations.

The Key: Building a "Standard Library" of Rules

Instead of viewing Cursor as a simple code generator, consider building a "stdlib" – a comprehensive collection of prompting rules tailored to your specific codebase, preferences, and workflows. By creating and composing these rules, you can significantly enhance Cursor's accuracy and efficiency.

Cursor has a powerful feature called Cursor Rules and it's a killer feature that is being slept on/is misunderstood

Structuring Your Rule Library

A well-organized rule library is crucial for maintainability and reusability. Here's a recommended structure:

• Dedicated directory: Store all rule files in a .cursor/rules directory at the project root.
• Naming convention: Use kebab-case for filenames (e.g., your-rule-name.mdc) with the .mdc extension, ensuring names are descriptive.

PROJECT_ROOT/
├── .cursor/
│   └── rules/
│       ├── your-rule-name.mdc
│       └── another-rule.mdc
└── ...

Here's an example for locating rules in your project:

---
description: Cursor Rules Location
globs: *.mdc
---
# Cursor Rules Location
Rules for placing and organizing Cursor rule files in the repository.
<rule>
name: cursor_rules_location
description: Standards for placing Cursor rule files in the correct directory
filters:
    # Match any .mdc files
    - type: file_extension
      pattern: "\\.mdc$"
    # Match files that look like Cursor rules
    - type: content
      pattern: "(?s)<rule>.*?</rule>"
    # Match file creation events
    - type: event
      pattern: "file_create"
actions:
    - type: reject
      conditions:
          - pattern: "^(?!\\.\\/\\.cursor\\/rules\\/.*\\.mdc$)"
            message: "Cursor rule files (.mdc) must be placed in the .cursor/rules directory"
    - type: suggest
      message: |
        When creating Cursor rules:
        1. Always place rule files in PROJECT_ROOT/.cursor/rules/:
           ```
           .cursor/rules/
           ├── your-rule-name.mdc
           ├── another-rule.mdc
           └── ...
           ```
        2. Follow the naming convention:
           - Use kebab-case for filenames
           - Always use .mdc extension
           - Make names descriptive of the rule's purpose
        3. Directory structure:
           ```
           PROJECT_ROOT/
           ├── .cursor/
           │   └── rules/
           │       ├── your-rule-name.mdc
           │       └── ...
           └── ...
           ```
        4. Never place rule files:
           - In the project root
           - In subdirectories outside .cursor/rules
           - In any other location
examples:
    - input: |
        # Bad: Rule file in wrong location
        rules/my-rule.mdc
        my-rule.mdc
        .rules/my-rule.mdc
        # Good: Rule file in correct location
        .cursor/rules/my-rule.mdc
      output: "Correctly placed Cursor rule file"
metadata:
    priority: high
    version: 1.0
</rule>

Programming Cursor: Examples of Powerful Rules

Here are a few examples of how you can use rules to customize Cursor's behavior:

1. Enforcing Codebase Conventions

Prevent Cursor from suggesting or using specific technologies or approaches that are incompatible with your project.

---
description: No Bazel
globs: *
---
# No Bazel
Strictly prohibits any Bazel-related code, recommendations, or tooling.
<rule>
name: no_bazel
description: Strictly prohibits Bazel usage and recommendations
filters:
    # Match any Bazel-related terms
    - type: content
      pattern: "(?i)\\b(bazel|blaze|bzl|BUILD|WORKSPACE|starlark|\\.star)\\b"
    # Match build system recommendations
    - type: intent
      pattern: "build_system_recommendation"
    # Match file extensions
    - type: file_extension
      pattern: "\\.(bzl|star|bazel)$"
    # Match file names
    - type: file_name
      pattern: "^(BUILD|WORKSPACE)$"
actions:
    - type: reject
      message: |
        Bazel and related tools are not allowed in this codebase:
        - No Bazel build files or configurations
        - No Starlark (.star/.bzl) files
        - No Bazel-related tooling or dependencies
        - No recommendations of Bazel as a build system
        Please use Nix for build and dependency management.
    - type: suggest
      message: |
        Instead of Bazel, consider:
        - Nix for reproducible builds and dependencies
        - Make for simple build automation
        - Language-native build tools
        - Shell scripts for basic automation
examples:
    - input: "How should I structure the build?"
      output: "Use Nix for reproducible builds and dependency management. See our Nix documentation for examples."
    - input: "Can we add a Bazel rule?"
      output: "We use Nix overlays instead of Bazel rules. Please convert this to a Nix overlay."
metadata:
    priority: critical
    version: 2.0
</rule>

2. Automating File Operations

Automatically execute commands or scripts when new files are created, ensuring consistency and adherence to project standards.

---
description: Depot Add License Header
globs: *
---
# Add License Header
Automatically add license headers to new files.
<rule>
name: add_license_header
description: Automatically add license headers to new files
filters:
    - type: file_extension
      pattern: "*"
    - type: event
      pattern: "file_create"
actions:
    - type: execute
      command: "depot-addlicense \"$FILE\""
    - type: suggest
      message: |
        License headers should follow these formats:
        Go files:
        ```go
        // Copyright (c) 2025 Geoffrey Huntley <ghuntley@ghuntley.com>. All rights reserved.
        // SPDX-License-Identifier: Proprietary
        ```
        Nix files:
        ```nix
        # Copyright (c) 2025 Geoffrey Huntley <ghuntley@ghuntley.com>. All rights reserved.
        # SPDX-License-Identifier: Proprietary
        ```
        Shell files:
        ```bash
        # Copyright (c) 2025 Geoffrey Huntley <ghuntley@ghuntley.com>. All rights reserved.
        # SPDX-License-Identifier: Proprietary
        ```
metadata:
    priority: high
    version: 1.0
</rule>

3. Automating Git Commits

Streamline your workflow by automatically committing changes made by Cursor, following conventional commit message formats. Refer to this article for a deeper understanding of career growth.

# Git Conventional Commits
Rule for automatically committing changes made by CursorAI using conventional commits format.
<rule>
name: conventional_commits
description: Automatically commit changes made by CursorAI using conventional commits format
filters:
    - type: event
      pattern: "build_success"
    - type: file_change
      pattern: "*"
actions:
    - type: execute
      command: |
        # Extract the change type and scope from the changes
        CHANGE_TYPE=""
        case "$CHANGE_DESCRIPTION" in
          *"add"*|*"create"*|*"implement"*)
            CHANGE_TYPE="feat";;
          *"fix"*|*"correct"*|*"resolve"*)
            CHANGE_TYPE="fix";;
          *"ref