Testing Claude’s Native Integration with Reminders and Calendar on iOS and iPadOS

Reminders created by Claude for iOS after a series of web searches.

A few months ago, when Perplexity unveiled their voice assistant integrated with native iOS frameworks, I wrote that I was surprised no other major AI lab had shipped a similar feature in its iOS apps:

The most important point about this feature is the fact that, in hindsight, this is so obvious and I’m surprised that OpenAI still hasn’t shipped the same feature for their incredibly popular ChatGPT voice mode. Perplexity’s iOS voice assistant isn’t using any “secret” tricks or hidden APIs: they’re simply integrating with existing frameworks and APIs that any third-party iOS developer can already work with. They’re leveraging EventKit for reminder/calendar event retrieval and creation; they’re using MapKit to load inline snippets of Apple Maps locations; they’re using Mail’s native compose sheet and Safari View Controller to let users send pre-filled emails or browse webpages manually; they’re integrating with MusicKit to play songs from Apple Music, provided that you have the Music app installed and an active subscription. Theoretically, there is nothing stopping Perplexity from rolling additional frameworks such as ShazamKit, Image Playground, WeatherKit, the clipboard, or even photo library access into their voice assistant. Perplexity hasn’t found a “loophole” to replicate Siri functionalities; they were just the first major AI company to do so.

It’s been a few months since Perplexity rolled out their iOS assistant, and, so far, the company has chosen to keep the iOS integrations exclusive to voice mode; you can’t have text conversations with Perplexity on iPhone and iPad and ask it to look at your reminders or calendar events.

Anthropic, however, has done it and has become – to the best of my knowledge – the second major AI lab to plug directly into Apple’s native iOS and iPadOS frameworks, with an important twist: in the latest version of Claude, you can have text conversations and tell the model to look into your Reminders database or Calendar app without having to use voice mode.

In an announcement earlier this week, the company focused on their integration with MapKit to discover nearby locations with Claude, but when I opened the app, I noticed that the splash screen mentioned “tasks and lists”, and I was curious to check it out. So I took some time off editing my upcoming iOS and iPadOS 26 review to see for myself, and from what I’ve seen so far, I’m impressed.

Claude’s splash screen on iPadOS.

Claude for iOS can now access Reminders to search lists, create or delete tasks, and modify existing tasks. All of this is based on Apple’s native Reminders framework with proper permission prompts, and Reminders gets treated by Claude as another tool that can be invoked in conversations alongside your location and the Calendar app. All of these new tools live in Claude’s settings under the new ‘Permissions’ page, where you can choose to enable read or write access for them and select whether they should run automatically or ask you for permission every time.

Given my previous experience with Claude Opus 4 and interleaved thinking steps for long-running tasks, I decided to take this feature for a spin with a moderately complex query. Here’s what I asked:

Search the web for Viticci’s annual iOS reviews over the years. I want you to find all links to the reviews I posted starting with iOS 9. Then, for each, create a reminder in my Work list, due in 15 minute increments starting at 5 PM today, with the title of the review as task name and the URL in the notes field of the reminder if you can.

Claude Opus 4.1 got to work and started searching the web for links to all of my reviews, starting with the one for iOS 9 from 2015. After finding all the links, it requested access to my Reminders and tried to create each task in my ‘Work’ list, but since it couldn’t find that list, it created all tasks in the default ‘Reminders’ one instead. Impressively, since Claude ran a separate tool to identify my current time, it managed to create tasks with 15-minute offsets in their due times like I asked, and it put the link for each review in the notes field of the task.

Claude’s Reminders permission prompt.

Reminders created (then moved) by Claude.

I figured out why Claude couldn’t find my ‘Work’ list: it was a newly created list with no tasks (completed or otherwise) inside it. After I created a sample reminder in the list and marked it as done, subsequent Claude sessions successfully found my ‘Work’ list.

I also tested Claude’s integration with the Calendar app, and after some back and forth, I got it to work. Initially, Claude kept defaulting to the existing Google Calendar integration in my account, but after I phrased my request as such:

What’s in my calendar for the next three days? Check the system Calendar app, not Google.

Claude understood that I wanted to work with the native Calendar app, successfully queried my list of events, and presented some results:

Events from the Calendar app in Claude.

Unfortunately, as is the case with other Reminders integrations in third-party iOS apps, Claude cannot access more modern app features like native rich links, tags, and subtasks. Every year, I keep hoping that Apple will create a proper “ReminderKit” framework for developers; until that happens, Claude and Perplexity will be stuck with this kind of basic integration.

I also took a look at the function-calling that happens behind the scenes when Claude retrieves and creates reminders on iOS and iPadOS. Funnily enough, when reasoning over the steps required to create a reminder in a specific list, Claude itself outlined all the Reminders tools at its disposal:

The user wants me to move the reminders to a Work list. However, when I searched for lists earlier, there was no “Work” list found. I should first create a Work list or search again to make sure, and then move the reminders there.

Let me search for all lists again to be sure there’s no Work list, and if not, I should inform the user that we need to create one first. I cannot create a new list with the current tools - I can only add reminders to existing lists.

Looking at the available tools, I don’t see a way to create a new list. I can only:

Search for lists (reminder_list_search_v0)

Create reminders in existing lists (reminder_create_v0)

Update reminders (reminder_update_v0)

Delete reminders (reminder_delete_v0)

I should let the user know that I cannot create a new Work list with the current tools, and they would need to create it manually in the Reminders app first.

In my experiments with Claude during this iOS review season – which I will write about in depth in the ‘Making Of’ story for my iOS review for Club members – I’ve noticed that it’s really helpful to know the names of the exact tools you want Claude to use, especially if you have several (or conflicting) integrations enabled. With these new Reminders tools, it’s going to be interesting to set up projects for hybrid automations that use a fixed set of function calls and the flexibility of a large language model.

So, five months after Perplexity’s iOS voice assistant, Anthropic has shipped their own take on iOS integrations that work with text chats. I keep thinking that this is an obvious route for major AI labs without their own ecosystem (i.e., Google) and that I’m surprised OpenAI hasn’t built anything along these lines for its ChatGPT iOS app yet. We’ll see!