Set up custom instructions once in your AI settings and every future conversation automatically follows the SRT-1 protocol — no thread starter needed, no copy-paste required.
ChatGPT has two separate fields. Copy each into the correct box:
Use this for: Perplexity, Mistral, LM Studio, Open WebUI, API integrations, or any AI that lets you set a system prompt.
| Platform | Custom Instructions | Project/Agent Mode | Character Limit | Mobile Sync | Notes |
|---|---|---|---|---|---|
?? Claude |
? Yes | ? Projects | ~2,000 | ? | Best instruction-following. Projects allow per-context instructions. |
?? ChatGPT |
? Yes (2 fields) | ? GPT Builder | 1,500 per field | ? | Two-field format. GPT Builder allows custom agents. |
?? Gemini |
~ Advanced only | ? Gems | ~1,000 | ? | Free tier limited. Gems provide richer customization. |
?? Copilot |
~ Limited | ? Copilot Studio | Varies | ? | Personal instructions limited; enterprise has full control. |
?? Any LLM |
? System prompt | ~ Depends | Model limit | — | Use Universal version as system prompt in any API call. |
You've got the permanent foundation with custom instructions. Add thread starters for focused new sessions and snippets for in-conversation tools.