Free tool
ChatGPT custom instructions, done properly
Not just "be concise." Start from your role, add the behavior directives most people never think to write, like ask before guessing and push back when I'm wrong, then fine-tune length, spelling, and your own rules. It runs in your browser and stays under ChatGPT's 1500-character limit.
Custom instructions have a ceiling
Give people an AI that actually knows your work
These shape how ChatGPT talks to you, but it is still just a prompt. It cannot read your real PDFs, your website, or your notes, and you cannot share it. A Mindola lens is trained on your own material, answers with sources, and lives on one link anyone can talk to.
The directives most people skip
Almost everyone sets tone and stops. The instructions that actually change answer quality are about behavior, and they live in the second field.
Ask before guessing
ChatGPT loves to answer a vague question with a confident guess. Telling it to ask one clarifying question first saves whole rounds of back and forth.
Push back when I'm wrong
By default it tends to agree with you. Inviting real disagreement is how you catch your own mistakes before they cost you.
Admit what it can't verify
A model that says "I'm not sure" is far more useful than one that invents a clean-sounding answer you then have to unwind.
Complete code, no placeholders
If you write code with it, "no ... or omitted sections" alone saves hours of copying fragments back together.
Questions
Custom instructions are two saved fields in ChatGPT that apply to every new chat: what it should know about you, and how it should respond. Set them once and you stop re-explaining yourself in every conversation.
Each of the two fields holds up to 1500 characters. This generator shows a live count against that limit so you can pack in the directives that matter without going over.
Open ChatGPT, go to Settings, then Personalization, then Custom instructions. Paste the "know about you" block in the first field and the "how to respond" block in the second.
The basics like "be concise" help a little. The bigger wins are behavior directives most people skip: ask a clarifying question before guessing, push back when you are wrong, admit what it cannot verify, and give complete code with no placeholders. Those change the quality of answers, not just the length.
Yes. Custom instructions are tied to your account, so they apply across the web app and the mobile apps once you save them.
No. Custom instructions only shape your own ChatGPT, and a shared ChatGPT link still runs on your account. If you want an AI that others can talk to on their own, trained on your material, that is a Mindola lens.