Beta Acid

At Beta Acid, we've been experimenting with integrating Large Language Models (LLMs) into our workflows for over two years now. For our engineering team, GitHub Copilot has been a productivity enhancer, but we've recently started noticing some persistent flaws:

• Partial code completions
• Seemingly worsening suggestions
• Inconsistent use of context from the codebase
• Too much copy/pasting into chat windows or other LLMs

A few months ago we began exploring new tools that better integrate into our development workflow. One tool that stood out is Cursor, a fork of VS Code that integrates LLM features throughout the IDE. What sets Cursor apart is its deep integration with context from your codebase, which dramatically improves code suggestions and completion accuracy.

Harnessing the Power of Context

Cursor’s ability to leverage context is its strongest feature. It pulls context directly from your codebase by indexing files and directories, which allows it to understand your project’s structure and dependencies. In addition to this automatic indexing, you can give Cursor additional context by using specific references in chat, such as pointing to files, code snippets, or external documentation.

Here are the main types of context that Cursor uses to improve your workflow:

• Codebase Indexing: Cursor indexes your entire codebase, providing it with some understanding of the project’s structure, functions, and classes. This allows the LLM to suggest code that is consistent with your project’s existing patterns and architecture.
• @files and @code: Use @files and @code to refer directly to specific files or blocks of code within your project. This ensures that Cursor can pull in relevant snippets or structural elements from your existing codebase.
• @docs: Calling @docs allows you to reference external documentation that Cursor can use to better understand your external dependencies. This is especially useful for libraries that change frequently and the LLM might have been trained on outdated material.
• @codebase: Use the @codebase symbol to reference your entire codebase contextually in chat. This is useful for tasks that require a broader understanding of your entire project, such as ensuring code consistency across different modules or suggesting improvements based on the overall architecture.

Pro Tips for Using Cursor Effectively

Let’s walk through how Cursor can help us enhance our FastAPI Reference App, which calls the Star Wars API and demonstrates best practices in FastAPI development.

1. Use the Chat Feature for Narrow Tasks

Rather than relying on Cursor’s Composer feature (which generates an entire feature at once), use the Chat feature to tackle smaller, more manageable tasks. You can refine your instructions within the chat and apply them to your file step-by-step. Taking it slow—one small chunk of code at a time—will help you better understand the changes and avoid unwanted behavior.

Letting Cursor build entire features looks great in marketing demos, but is a recipe for trouble in professional development.

2. Choose the Right Model for the Task

For day-to-day code generation and chat interactions, we recommend using Anthropic’s Claude 3.5 Sonnet. It provides the best balance between quality, cost, and speed for routine development. For more in-depth architectural planning, enable usage-based pricing to utilize Open AI’s o1 model. It costs $0.40 per request but provides great results.

3. Add Custom Documentation for Better Context

If the documentation you need isn’t available by default in Cursor you can add it manually and Cursor will scrape and index it for future use. For example, Cursor doesn’t include MJML docs out of the box, but you can have Cursor index the docs to improve code suggestions. Just press CMD+L, type @Docs, select "Add new doc", and provide the URL for the documentation. Cursor will scrape and index the content, allowing you to reference it in chat using @docs.

4. Add a .cursorignore File to Skip Unnecessary Files

You can use a .cursorignore file to tell Cursor to ignore specific files or directories when using the @codebase command in chat. This prevents Cursor from pulling in irrelevant parts of your project, helping it focus on the files that matter most and providing cleaner, more relevant suggestions.

5. Define Team Preferences with .cursorrules

Use a .cursorrules file to standardize how Cursor interacts with your project. This file provides context for each request you make, ensuring consistent code styles and preferences across your team. Sharing these rules helps maintain a cohesive workflow. For inspiration, check out this curated list of .cursorrules files that can be adapted to your team's needs.

6. Provide Clear and Detailed Instructions

When asking Cursor to generate code, provide as much relevant context as possible. For instance, in our reference app we’ve already build a characters endpoint, and now we want to add a new route to manage starships:

1. Create a new file for the route.
2. Press CMD+L to open the chat.
3. Describe your task: "Create a new /starships route that retrieves a list of starships added in the last 24 hours. Use the existing CharacterService and follow the patterns from the /characters endpoint. Implement pagination to limit the results per page, include sorting by creation date, and ensure error handling for when no starships are found. Add validation to check that the created_at field is within the past 24 hours, and update the router to include the new route."

Providing this level of detail will help you get 80% of the way to a working endpoint. Vague prompts like “Create a starships route” won’t follow your existing project structure.

7. Use Notepads for Common Tasks

If you’re frequently asking Cursor to perform similar tasks, the Notepads feature can streamline your workflow. For example, create a Notepad for “AddingNewRoute” in your Star Wars API. This could include common patterns like router structures, service layers, and database calls.

To set up a Notepad, go to Composer > Control Panel > Add Notepad, and store relevant code snippets and file references. When you’re ready, simply reference it in chat using @notepad for consistency across tasks.

8. Don’t Blindly Trust Results

After receiving multiple accurate results from Cursor, it can be tempting to start accepting suggestions without a thorough review. This is a mistake. LLMs can still introduce bugs and hallucinate, particularly when refactoring or suggesting code changes.

• Bugs: Even after several successful interactions, review everything carefully. We’ve encountered cases where Cursor changed a file path in a refactor without realizing the template it altered didn’t match.
• Non-Optimal Solutions: Cursor may suggest viable but inefficient solutions for your platform. Rely on your expertise to adjust these suggestions to follow best practices.

Conclusion

At Beta Acid, we’re always looking for ways to boost productivity, and while Cursor is a great tool, it’s not magic—it’s simply a smarter interface for working with LLMs. It helps streamline workflows, but ultimately, it's you, the developer, driving the results. Use Cursor’s features to your advantage, but stay grounded—thoughtful engineering always comes first.