Apple has opened Siri AI to every app developer, and that brings Siri AI calendar actions a step closer to the phone in your pocket. Soon you will be able to ask Siri to find a free hour, move a meeting or book a call, and it will act across your apps for you. That is great news, with one catch for anyone who works across several calendars: an assistant can only protect the time it can see.
What Apple announced
On 3 November, Apple announced that Siri AI is now open to all developers. Starting with the iOS 27.3, iPadOS 27.3, macOS 27.3 and visionOS 27.3 betas, a Developer Preview lets any app bring its content and actions into Siri AI through App Intents. A new feature called skills lets developers teach Siri how to chain several actions into one task, and Siri can now find content from any app indexed in Spotlight, not only content that fits one of Apple’s predefined types.
It has been a long road. Apple first promised a Siri that takes actions in and across apps at WWDC in 2024. Customers get the new features “in a few months”, and apps can only ship their Siri integrations once App Store submission opens in the spring.
There is fine print, too. According to Apple’s developer documentation and reports from PPC Land and IT Brief, Siri AI works in six languages, isn’t available in the EU on iOS, iPadOS or watchOS, and isn’t available to users under 13. Features that run on Apple’s servers have daily usage limits, and Apple says expanded access “will be available for a fee in the future”. Terms and usage policies for these experiences are still to come.
What Siri AI calendar actions mean if you juggle several calendars
Siri can already work with Apple’s own apps, Calendar among them. Add third-party apps, and you have an assistant that can read an email in one app, check your schedule in another and send an invite from a third, all from a single sentence. For most people, that is a real time saver.
Now picture a typical week for a consultant. Client work lives in the client’s Microsoft 365 account. The agency they subcontract for uses Google Workspace. The school run and the dentist sit in a personal Google Calendar. You ask your assistant: “Find me an hour with Sam on Thursday.” It checks the calendar it knows about, sees Thursday at 2pm wide open, and books it. Except Thursday at 2pm is a client workshop, in a calendar the assistant never looked at.
That is not a Siri problem. It is a split calendar problem, and every assistant inherits it. Each connected account is an island, and an assistant acting on one island will happily book over a meeting on another. The faster and more capable assistants get, the faster they can double-book you.
We think this is where things are heading anyway. The calendar app you click through matters less every year, because your assistant does the clicking for you. What matters is that the data it reads is right. When an agent is the one checking your availability, “busy” has to mean busy everywhere, in every calendar it might look at.
Where Calendrz fits
This is the problem Calendrz was built to solve. With availability mirroring, when you are busy in one calendar, Calendrz automatically blocks that time in all your others, across Google Calendar and Microsoft 365. Each block is a simple “Blocked” marker with none of the private details, so a client never sees what you are doing for another client. Whichever calendar an assistant reads, the free slots it finds are genuinely free, and your time is protected everywhere, whoever (or whatever) does the booking.
For assistants that speak MCP, such as Claude, we go a step further. The Calendrz MCP server gives an AI assistant one view of every connected account: it can find free slots, create and move events and respond to invites across all your calendars, not just one of them. Agents are only as useful as the context you give them, and when they book your time, your full availability is the context that matters most.
Get ready before your assistant starts booking
Siri AI’s app actions reach customers in the coming months, and other assistants are moving just as fast. If your week is spread across several calendars, now is a good time to make sure each of them tells the truth about when you are free. Connect your calendars to Calendrz in a couple of minutes, and let auto-blocking keep every one of them up to date, so the next meeting your assistant books lands in time that is actually yours.
