The same prompt can produce a great answer in one AI model and a mediocre one in another. Here's why, and how to adjust your approach for GPT, Claude, Gemini, Grok, and the open-weight models.
If you've ever copied a prompt that worked great in one AI tool into another and gotten a worse answer, you're not imagining it. In our guide to understanding the different AI models, we covered which model is strongest for which job. This post covers the other half of the equation: once you've picked a model, how do you actually talk to it well?
TL;DR: Structure and clarity help on every model, but each lab tunes its model to respond best to a slightly different style. Claude tends to reward explicit structure and step-by-step reasoning requests. GPT responds well to role-based framing and iterative refinement. Gemini benefits from being explicit about the format you want back. Grok does best with direct, conversational instructions. Open-weight models generally need more explicit instructions since they've had less fine-tuning polish.
Every model is trained on a different mix of data, fine-tuned with different techniques, and optimized for different default behaviors. Some are tuned to be terse by default; others are tuned to add caveats and structure unless told otherwise. A prompt written for one model is really a prompt written for that model's specific training, and moving it to another model without adjustment is one of the most common reasons people conclude a model is "worse" when it's actually just being spoken to in the wrong dialect.
Open-weight models like Llama, DeepSeek, Qwen, GLM, and Kimi generally need more explicit instructions than the top proprietary models, since they typically have less fine-tuning polish layered on top of the base model. Being very specific about format, tone, and constraints matters more here than with a flagship proprietary model, which is more likely to infer what you want from a shorter prompt.
Do I need to write a completely different prompt for every model? Not from scratch, but you should expect to adjust it. A prompt that works on Claude will often work reasonably well on GPT or Gemini with minor tweaks to formatting and directness, rather than needing to be rewritten entirely.
Does prompt engineering still matter as models get smarter? Yes, though the bar has moved. Today's models are more forgiving of vague prompts than earlier generations, but clear, specific instructions still produce meaningfully better results, especially for complex or high-stakes tasks.
What's the single highest-impact thing I can do to improve my prompts? Give the model an example of what a good answer looks like. It's usually more effective than adding more instructions.
Should I use the same prompt style for a "flash" or "mini" model as I do for a flagship model? No. Smaller, faster models generally do better with shorter, more direct prompts, while flagship and reasoning-tuned models can handle (and often benefit from) more detailed, structured instructions.
Last updated: July 27, 2026. Prompting best practices evolve as labs update their models, so check each provider's official documentation for the latest recommendations.