Projects, Instructions and Memory: Customise Your Assistant

If every time you open the assistant you have to explain who you are, what you do and how you want answers, you’re wasting time. All three major assistants have a way to save that context: ChatGPT and Claude projects, and Gemini Gems. Set up well, they turn a generic chat into a specialised assistant.

What each one is

Feature	What it keeps	Where
Project	Conversations, files and instructions for one topic	ChatGPT and Claude
Gem	Instructions and files for a custom assistant	Gemini
Custom instructions	How you always want it to answer	Each assistant’s settings
Memory	Facts about you remembered across chats	ChatGPT, Claude and Gemini, if enabled

In practice: use instructions and memory for what applies everywhere (your language, your job, no jargon) and a project or Gem for each recurring job (your online shop, your thesis, the classes you prepare).

Step 1: create a space per topic

• ChatGPT: in the sidebar, New project. Also available on the free plan, with file limits: 5 on Free, 25 on Plus and Go, 40 on Pro.
• Claude: Projects → Create project. The free plan allows up to five projects; paid plans can handle much more material because Claude searches within it (RAG).
• Gemini: on gemini.google.com, open the sidebar, Gems → New Gem. Custom Gems are created and edited on the web.

Step 2: write good instructions

Instructions work like a system prompt: they apply to every conversation in the space. A good template:

“You are my assistant for [topic]. I am a [role] working with [audience]. Always answer in English, in a [tone] tone, with short sentences. When information is missing, ask before assuming. Default format: [list, table, email draft…]. Never invent facts: if you don’t know, say so.”

Gemini can help you improve a Gem’s instructions while you create it. In any assistant, asking “improve these instructions so they’re clearer” works.

Step 3: upload reference material

Add the documents the assistant should always consult: your company style guide, the syllabus, the product catalogue, your customers’ FAQs. Tips:

• Fewer, better files. Tidy, up-to-date files work better than a folder of drafts.
• Clear names: “catalogue-autumn-2026.pdf”, not “final doc v3 (2).pdf”.
• Nothing sensitive that shouldn’t leave your company, unless you use a business plan with the right guarantees.

Step 4: work inside the space

Open every conversation on the topic inside the project or with the Gem. It starts from the instructions and files without you repeating them. In ChatGPT, projects can also use earlier chats in the same project as context, and there is project-only memory so it doesn’t mix with everything else.

Step 5: memory, used wisely

Memory makes the assistant remember details about you (for example, that you’re a primary-school teacher or prefer short answers). It’s handy, but:

• Check what it remembers now and then: in settings you can see and delete each memory.
• For sensitive topics, use a temporary or incognito chat, which isn’t saved to memory.
• Read how agent memory works to understand its limits.

Common mistakes

• Contradictory instructions (“be brief” and “explain everything in detail”). Pick one.
• One project for everything. Mixing topics worsens answers; several small spaces work better.
• Not updating files. If the catalogue changed, the assistant will keep quoting the old one.