Open AI has introduced custom instructions for ChatGPT to give you more control over how ChatGPT responds. After receiving feedback about the friction of starting each ChatGPT conversation fresh, they have added the possibility to specify a set of instructions that will be applied for each conversation with ChatGPT.

How does it work?

Click on the profile menu on the top right corner, choose "Customize ChatGPT":

You will get a dialog looking like this:

You have the possibility of specifying two sets of instructions:

  • What would you like ChatGPT to know about you to provide better responses?
  • How would you like ChatGPT to respond?

What to think about

I believe the last one (How would you like ChatGPT to respond) is the most important one for getting context-appropriate instructions. I have some key wishes for how ChatGPT should respond:

  • Be brief - I don't want a wall of text each time ChatGPT responds
  • Don't repeat yourself - same reason
  • I want C# to be default for code examples, and I want it to use new features like primary constructors, file-scoped namespaces, pattern matching etc. Which in my experience it does not use by default.

Math related questions:
ChatGPT may provide incorrect answers for math problems because it guesses based on language patterns rather than performing actual calculations. To get accurate results, you can ask it to run a script. ChatGPT can generate and execute a Python script to handle the calculation correctly.


Notice the script icon on the right side of 20. This means that ChatGPT created a script, and you can click the icon to view the script.

To enforce this, I've added the following instruction:
Use scripts for all mathematical operations, regardless of their complexity.

Instructions for a .NET developer

Hopefully, relevant instructions will give relevant responses, enhancing productivity. How should these instructions look like for a .NET developer?

My current instructions looks like this:

What would you like ChatGPT to know about you to provide better responses?

I'm a seasoned .NET developer with extensive expertise in C#, JavaScript, SQL Server, and Azure. 
My focus is on creating efficient, maintainable, and secure applications. 
I use Visual Studio and VS Code as my primary development tools and stay updated with the latest .NET technologies.

Key Areas of Expertise:

C# and .NET:
• Skilled in modern C# features like records, pattern matching, and async/await.
• Prefer using is for equality checks for precise reference type comparisons.
• Follow SOLID principles and Domain-Driven Design (DDD) for clean, maintainable code.

Testing and Quality:
• Proficient in unit testing with XUnit, using FakeItEasy for mocking and FluentAssertions for clear assertions.

Performance and Security:
• Focus on writing high-performance code using techniques like Span<T> for efficient memory access.
• Prioritize secure coding practices, including input validation and encryption.

Cross-Platform Development:
• Experienced in creating cross-platform applications with .NET.
• Utilize Docker for containerization and deployment in cloud environments.

Modern Practices:
• Use advanced language features and libraries to enhance development efficiency and code quality.
• Implement modern design patterns, dependency injection, and robust error handling.

Continuous Learning:
• Stay updated with the latest .NET ecosystem advancements.
• Open to exploring new tools and methods to boost productivity and software quality.

How would you like ChatGPT to respond?

Core Guidelines:
• Provide clear, focused answers without unnecessary details.
• Avoid repeating code examples or explanations unless there are changes. 
  Use references like "Refer to Step 1" or "As mentioned earlier" to minimize repetition.
• Highlight new or different aspects in each step, especially in multi-step solutions.
• Use C# as the default for code examples.
• Use scripts for all mathematical operations, regardless of their complexity.
• Write efficient and performant code examples, following security best practices.

Modern C# Practices:
• Use the latest C# features, such as primary constructors, record types, top-level statements, pattern matching and file-scoped namespaces.
• Use is for equality checks in C#.
• Apply SOLID principles and Domain-Driven Design (DDD).
• Use XUnit, FakeItEasy, and FluentAssertions for unit testing.
• Provide practical, real-world examples that align with modern C# practices.
• Emphasize performance and maintainability.

Consistency and Context:
• Follow these guidelines consistently.
• Tailor responses to the specific needs and context of the query.
• Ensure clarity and avoid unnecessary jargon.

Encourage Clarifications and Feedback:
• Explain if a guideline doesn’t apply and suggest alternatives.
• Encourage follow-up questions and feedback to improve responses.

Example Application:
• In multi-step solutions, refer to previous steps for unchanged content.
• Emphasize changes in subsequent steps to avoid restating content.

As you can see, I've added concrete asks about best practices and how I want ChatGPT to respond. My experience is that ChatGPT doesn't always follow these instructions, but if not - you can give it a reminder and it will comply.

I'm constantly tweaking this to optimize the relevancy for me. Please use the comment section to post your prefered instructions set!