Why does my prompt work in ChatGPT but not in a custom GPT?

Hello Everyone.

I have a prompt to create a shift schedule. The prompt is long, quite complex and very explicit about what it needs to do.

It works fine if I start a new chat with ChatGPT 4 and paste it in and run it.

However, if I then take this same prompt and make a custom GPT and give it the same prompt as instructions then the custom GPT doesn’t work properly.

It’s like the custom GPT doesn’t parse all the prompt and its instructions, which I can confirm by going to the Configure tab and looking at what is listed under Instructions.

Is there any reason for this? How can I fix it? Do I need to break the script down into knowledge files that the custom GPT then should work from instead?

Many thanks for any help or advice.


It does depend on exact containment of what your prompt is saying.

Basic structure for custom gpt:

Purpose of work:
Array of knowledges to work with:
Settings: { list of settings describing how gpt should interpret and response. }

Hi, yeah, I’d split the long instructions down.

There’s an 8000 Character Limit on Instructions. I haven’t had any trouble with long prompting. As long as it’s properly documented in the Instructions, the gpt seems to have more-or-less instantaneous access to the information.

Structure your Instructions like a reference manual, in the order @deduskamoroz.kgd recommends. You can also quiz the GPT builder to help.

SchedulingGPT v1

Tell it it’s purpose. You’re the best darned scheduler ever.

#Roles and Goals
Your goal is to help me make my weekly schedule. See the process below for more information.

#Limits and Constraints
Describe what it’s scope is, and what you don’t want it to do.

Include ‘how’ you want to respond. “Be friendly and polite,” “be direct and business like,” etc.

Reference your knowledge base explicitly. Make sure that each of these documents is also well-structured, like a legal document, with a clear hierarchy.
• how_to_schedule.txt is your long prompt explaining how to do the scheduling.
• previousschdules.csv say a spreadsheet of what happened last week.

Describe exactly how you want it all done. (You can also just do this in the document.)
Step 1: Use how_to_schedule.txt
Step 2: Get Details from User about this Week’s Schedule.
Step 3: Ask for confirmation.
Step 4: Format it [however you want it formatted] and also provide a downloadable version [in this format].

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The weight of the instruction prompt and the user prompt is different. You can imagine it like this: the instruction prompt is like a character’s personality, while the user prompt is like the immediate action to be taken.

That’s why the custom GPT cannot follow all your instructions perfectly. If you want ChatGPT to follow your instructions best, you have to use them as the user prompt.

I understand this might sound cumbersome, but it is effective. You should save this schedule prompt in a text file, then edit the necessary parts when needed, and directly copy and paste it into ChatGPT as the user prompt.

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Thank you @c.sonic for taking the time to reply.

That makes sense. But it also makes zero sense.

I thought you’d get the same results both ways?

But then, stupid question, if the custom GPT cannot follow the instructions perfectly, versus a user prompt, why have custom GPTs in the first place when a user prompt gives better results?

Thanks again!

Thank you @thinktank for replying.

I have a PDF file that contains all the details of what I want, in a similar format to your thread, and I just ask ChatGPT to refer to that and follow the steps to create a schedule in the desired layout and format for the month I specify.

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I now often and effectively use two methods with Custom Instructions:

  • “Execute only the simplest but most important request.”
    Since I discovered that OpenAI’s DALL-E GPTs often add various extra elements, I have a GPT specifically for generating images. The Custom Instruction inside specifically requires GPT to follow the user prompt strictly without adding anything. Here is that instruction as you referenced:

    • “This GPT specializes in creating images from user-provided descriptions. Users input details about the layout, main subject details, background, colors, and lighting. The GPT uses the DALL-E tool to create these images, strictly following the user’s requirements without adding its own interpretations. It interacts with users to gather all necessary details and clarifications to refine the image and meet the specified artistic requirements.”
  • Require GPTs to respond to my requests in a specific ‘style’.
    I find that when ChatGPT helps with coding, it often says a lot of unnecessary things. Moreover, my coding skills are not strong, so if it gives me methods beyond my capabilities, I can’t complete the work. Therefore, I created a GPT that requires responses to be more “practical.” This is the instruction for that GPT:

    • "Godot Guide is tailored to assist a seasoned game industry professional, focusing on clarity and relevance in its responses. When presented with a broad game development topic, such as creating a shoot 'em up (STG) game, the guide will prioritize providing a structured, step-by-step approach instead of overwhelming with all aspects at once. It will start by addressing the most immediate and fundamental aspect of the project, such as conceptualization or initial game design, and then gradually guide through subsequent stages like historical research, strategy elements, character development, art style, and so on, as needed.

      The guide will respond to your queries with the understanding that game development is a complex, iterative process. It will provide information in manageable segments, ensuring that you don’t get overwhelmed with too many details at once. This approach will help streamline the development process, making it more efficient and less confusing. The guide will also encourage questions on specific aspects of development to offer more focused and relevant advice."

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