Most of what fills a Mac is explained by the catalog: entries written and checked by hand, with their sources. For an item no entry explains, the inspector can ask Apple Intelligence, on your Mac, for a Best guess at what it is.
When it's used
- Only for items no entry explains. Items the catalog explains keep its reviewed words, so a guess never contradicts them.
- Only when you ask. Select the item and click Explain in the inspector's Best guess section. Nothing is sent to the model before that.
- One at a time, in the app only. The menu bar item never uses it. An answer that takes longer than a minute is given up.
The answer is saved, so the item shows it straight away next time, with Explain Again if you want a new one. The app keeps the latest 500 answers.
What a Best guess says
- what the item probably is, in a sentence or two
- Looks like: the kind of item, such as a cache, logs, app data, media, an installer, a backup or developer files, or "Can't tell"
- Probably made by: the app it probably belongs to, when it can tell
- Made again by its app, shown with the app: "Probably", "Probably not" or "Can't tell"
Under it, the app always says: "Written on this Mac by Apple Intelligence. It can be wrong." If the item has changed a lot since the answer was written, it says that too.
What it never does
A Best guess never says whether something is safe to delete, and it never decides anything. Items no entry explains are never offered for removal, whatever a guess says about them.
Before an answer is shown, the app takes out any sentence that gives a verdict ("safe to remove"), advises deleting, contains a Terminal command, or uses words like junk, clutter, bloat or wasted space, and any app identifier or version the facts didn't contain. It says "made again by its app" only for caches and logs, and never for anything in your own folders or cloud storage.
What the model is given
The model gets facts from the scan, never the contents of your files:
- the item's path, size, number of items and dates
- the names and sizes of the largest items inside, and which name extensions are common there
- the app a bundle identifier in the path names, and whether that app is installed
- the catalog entries that explain items inside it
The model runs on your Mac. Nothing about your files leaves it.
Which Macs have it
Best guess needs a Mac with Apple Intelligence, turned on in System Settings › Apple Intelligence & Siri. When it's off, the inspector says so; while macOS is still downloading its models, it says to try again later. On Macs that can't run Apple Intelligence, the section doesn't appear.
It's part of the free analyzer.