Tell Gemini how you want something written and that preference can carry into other Workspace apps. Google’s 2 September announcement extends custom instructions to Drive, Chat, Gmail, Sheets and Slides, following their introduction in Docs.

Users can save an instruction through conversation or edit the list under Settings → Personalization. The linked help page says saved instructions are shared across eligible Workspace products, including Gmail and Docs. They are separate from the instructions in the standalone Gemini Apps, which do not sync with this Workspace set.

That sharing is beneficial: you can set a preference for tone or formatting once and use it across the tools where you work. It also broadens the effect of an instruction that felt appropriate in one conversation. A preference for short answers might suit a routine email and be less useful when a contract summary needs to retain exceptions.

The instructions are visible to the person using Gemini. Google says they can inspect which ones were used by opening Sources beneath a response and looking under Personalization settings. They can also turn instructions off or delete them. Saving an instruction conversationally puts it in settings; it does not make it an invisible rule.

Author visibility is only part of the workflow, though. A colleague reading the resulting email or document is not necessarily looking at that Gemini response and its Sources panel. If a summary will support a consequential decision, the author still needs to check the source material and keep the relevant qualifications. Personalisation is no substitute for that review.

Google’s announcement says there is no admin control for this feature, while its help page describes administrator-controlled access to Gemini Beta. The pages also differ on availability. If you manage a Workspace domain, check the settings and availability in your own tenant before writing policy around the launch. Ask Google which documented access conditions apply and what administrative visibility exists for saved instructions. For users who have the feature, reviewing the shared instruction list is already a practical step.

When reviewing the saved list, I would first check for instructions that tell Gemini to sound certain, omit caveats or apply a business rule everywhere. A formatting preference is easy to understand; an instruction that changes which information survives into a summary needs more care. The useful outcome is a set of defaults people can inspect and explain when their work moves from one app to another.