Gemini (grounded search)
By Şamil Quliyev · Updated 2026-09-15
Gemini can answer from the model alone or ground its answer in Google Search, and it decides per query which to do. When grounding is used, the response carries grounding metadata — the search queries it ran and the sources it used — which makes the measurement unusually auditable.
How it picks sources
Grounded answers are built from Google Search results, so classic search visibility feeds into it more directly than in other engines: pages that rank and answer clearly are the ones that get pulled into the synthesis. The model then compresses several sources into one paragraph, and brands that are described in one plain sentence survive that compression better than brands described through marketing narrative.
Grounding behaviour
Conditional, like ChatGPT Search, but the decision leans on whether the query looks like it needs current or verifiable information. The practical consequence is that brand-name queries and best-of queries can behave differently — one grounded, one not — inside the same prompt set.
How to track it
Use the grounded-search configuration in the API, keep the grounding metadata with each stored answer, and compute rates only over answers where grounding actually occurred. The metadata also tells you which query the model ran, which frequently explains a surprising answer better than the answer text does.
Measurement mistakes
- Assuming Gemini and Google AI Overviews are the same surface. They are different products with different triggering behaviour, and tracking one does not cover the other.
- Dropping the grounding metadata when storing answers, which throws away the only reliable record of whether the answer was grounded at all.
- Reading a fall in mention rate as a content problem when the grounded share fell — the engine changed behaviour, not your visibility.
What TAMGIO measures here
This engine is part of TAMGIO ongoing tracking: prompts are sampled on it every cycle.
Frequently asked questions
- Does Gemini ground every answer?
- No. Grounding is decided per query, so a prompt set will contain a mix of grounded and ungrounded answers, and the mix itself shifts over time.
- Is Gemini visibility the same as Google ranking?
- Related but not the same. Grounded answers draw on Google results, so ranking helps, but the model still chooses which of the retrieved pages to lean on, and clarity of the stated fact often beats position.
