You'll leave with: your agent saved in at least one tool, ready to run with one click.
The problem: retyping and drifting
If you paste the same instructions every time, you waste effort, and small edits creep in. The fix is to save the instructions once, then start chats that already have them.
Option A: a ChatGPT Project
- OpenAI's help center says Projects keep related chats, files, and instructions together, and that project instructions apply within that project.
- To add instructions: open the project, use the “•••” menu, then Project settings.
- Projects are included with qualifying plans at no extra charge, you can create an unlimited number of them, and the Free plan allows 5 files per project (higher on paid plans). This is as of OpenAI's page when we checked.
Steps: New project → name it after your agent → open Project settings → paste the agent pack into the instructions → start a chat inside the project.
Option B: a Claude Project
- Claude's help center says projects are self-contained workspaces with their own chat histories and knowledge, and that they're available to all users including free accounts, with a maximum of five projects on a free account.
- You can add project instructions to tailor responses.
- Sharing projects with others is for Team and Enterprise plans, so don't promise “share this with friends” on a personal plan.
Steps: Create a project → add the pack to its instructions → add any reference files → start chats in it.
Option C: a Gemini skill
- Google says skills are reusable custom instructions. You use one by typing
/and its name in any Gemini chat, and they can be stacked. - Google's Sept 30, 2026 announcement says skills are available to all Google AI subscription tiers, currently for people 18+.
- Gems are being replaced: per Gemini Help, personal accounts 18+ see Gems become read-only on November 17, 2026, and Gems are removed on December 17, 2026. Google says it will automatically recreate your Gems as skills.
Steps (from Google's guide): in Gemini, open Customize Skills → Create → Create manually → add a name, a description (when to use it), and the instructions → Create. Keep the description specific, and add an example of the output you expect.
Why we don't build on custom GPTs or Gems
- Custom GPTs: OpenAI's FAQ says custom GPTs are scheduled to retire on Dec 11, 2026 (a later date applies to some enterprise workspaces), with migration to plugins that bring reusable instructions, files and connected apps together.
- Gems: as above, going away in December 2026.
The durable format is a plain-text prompt pack that works anywhere. If a platform changes, you copy the text somewhere else. That's why every agent in our library is a copyable pack.
Name and describe it well
| Field | Good | Weak |
|---|---|---|
| Name | Dinner Planner | Helper 3 |
| Description (when to use it) | “Use when I want a dinner plan with a grocery list and a budget.” | “Food stuff” |
| Instructions | The full pack | “Be helpful” |
Exercise
Save one agent from the Agent Library in a tool you actually use.
- Choose the tool (ChatGPT Project, Claude Project, or Gemini skill).
- Paste the pack, give it a clear name, and write a one-line “when to use” description.
- Run it twice in fresh chats. Does it behave the same?
- Write the date and the tool in your prompt log, so you know where it lives.
Bonus: do you have an existing custom GPT or Gem? Copy its instructions into a plain text file today.
Key takeaways
- Save instructions once in a Project or skill instead of retyping.
- Use plain-text prompt packs: they survive platform changes.
- Custom GPTs and Gems are being retired in December 2026.
Related: Pick an agent to save
Sources
- OpenAI Help Center: Projects in ChatGPT
- Claude Help Center: What are projects?
- Gemini Apps Help: About the transition from Gems to skills
- Google blog: Let skills in Gemini tackle your most repetitive tasks (Sep 30, 2026)
- OpenAI Help Center: Custom GPT retirement and migration FAQ
Checked November 10, 2026 (Eastern Time). Plans, limits and features change: confirm on the official page.