Summarize a Long Deck and Draft a Rationale Slide with Gemini in Slides

What This Does

Two jobs that eat time before a review: getting the gist of a long deck someone else built, and adding one rationale slide to your own deck. Gemini in Slides can summarize the presentation in the side panel and can draft a slide from a Google Doc in your Drive. This is not the same as building a whole deck from scratch. You keep the deck you have and add one slide to it.

Before You Start

• Gemini in Google Slides is available on your account. Google's help page says it needs an eligible Google Workspace or Google AI plan (Business Standard is the starting Workspace plan, at $14/user/month). You will see an Ask Gemini button at the top right of a presentation if you have it. If not, ask your Workspace admin.
• Your rationale is in a Google Doc in your Drive.
• Check your agency's AI policy and the client contract before you open unreleased decks with Gemini. Decks often hold concepts, schedules and launch dates under NDA. Also check your Workspace data settings with your admin, since an enterprise setup is not the same as a personal account. If in doubt, work from a copy where the client and product are replaced with code names.

Steps

1. Open the deck and Ask Gemini

Open the presentation in Google Slides on your computer. At the top right, click Ask Gemini. Google's page says that when you open a presentation that has text, the side panel shows a summary of it.

2. Ask for the summary you need

In the prompt box, type what you want, for example: "Summarize this presentation in 5 bullet points, then list any dates, sizes and names of deliverables it mentions." Press Enter. Google's page uses the prompt "Summarize this presentation in 3 sentences" as its own example. A summary can only reflect what Gemini can read, so check that image-heavy slides are not under-represented.

3. Check the summary against the deck

Click through the slides with the summary beside you. Look for anything missing (a date, a size, an open question) and anything stated that is not on a slide. Do not paste the summary into an email until you have done this.

4. Draft one rationale slide from your Doc

Click Ask Gemini again, or use Help me create a slide in the toolbar. Google's page lists that option in the toolbar and under both Insert and Slide in the menu bar. In the side panel, reference your Doc with @, as in the page's example "Create a slide about doc @Core Team sync." For example: "Create a slide for the Why it works section of @Lantern rationale. Use three short bullets that restate only what the Doc says." The page says new slides use your current theme. If the first result is off, the page suggests adding a Drive file with @ for more context, or using "Match presentation style" to reference another deck for format.

5. Insert it, then check every sentence

Click Insert to add the slide. Then read each sentence against your Doc. Remove anything that is not in the Doc. Gemini may add a claim, a comparison or a result. Those belong to the copywriter and the client's approved claims list, so nothing goes on the slide unless it is already there.

6. Keep generated images out of client work

Gemini in Slides can also create images from the side panel, per Google's page. Do not use those in client work unless your agency's legal team has cleared the tool. Use your own boards and layouts on the slide.

Real Example

Scenario: A 40-slide deck from last quarter's invented Project Lantern review lands in your inbox, and you need the gist before a call. Separately, your creative director wants a single rationale slide added to your current deck.

What you do: Open the old deck, ask for a 5-bullet summary plus a list of deliverables and dates, and check it against the slides. In your own deck, ask for a rationale slide from @Lantern rationale.

What you get: A short summary you can verify in a few minutes, and one slide with three bullets. You delete one bullet that mentions an audience size that is not in your Doc, and place your hero board beside the text.

Tips

• Google's page says you lose your Gemini conversation history when you refresh, close and reopen the presentation, or go offline, so insert anything you want to keep.
• Use Retry for a different version instead of rewriting your prompt.
• Gemini's suggestions are drafts. Google's own page says they may be inaccurate.

Tool interfaces change. If a button has moved, look for similar Gemini or Ask Gemini options in the same menu area.