Apple Events MCP Server

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A Model Context Protocol (MCP) server providing native integration with Apple Reminders and Calendar on macOS via the EventKit framework. Exposes reminders, lists, subtasks, and calendar events through a standardized interface with full CRUD operations.

The EventKit backend is the standalone event Swift CLI, vendored as a git submodule and built into bin/event during pnpm install — no separate brew install required. See docs/migration-to-event-cli.md for the v1.5.0 backend swap and the list of write fields not yet exposed by event.

Table of Contents

• Features
• Prerequisites
• Quick Start
• Configuration
• macOS Permissions
• Usage Examples
• Write confirmation and untrusted data
• Available MCP Tools
• Structured Prompt Library
• Development
• License
• Contributing

Features

• Full CRUD for reminders, subtasks, reminder lists, and calendar events
• Priority (high/medium/low/none), tags, and checklist subtasks with progress tracking
• Multi-criteria filtering: completion, due-date range, priority, tags, full-text search, recurring, location-based
• Flexible date formats (YYYY-MM-DD, YYYY-MM-DD HH:mm:ss, ISO 8601) with timezone awareness
• Native macOS integration via EventKit — values configured in Reminders.app / Calendar.app round-trip through read responses
• Automatic macOS permission discovery and prompting
• Full Unicode support with comprehensive input validation

Prerequisites

• Node.js 20 or later
• macOS (required for EventKit)
• Xcode Command Line Tools (only when building from source)
• pnpm (recommended)

The published npm package ships a pre-built, universal, code-signed bin/event binary, so npx users need neither Xcode nor a Swift toolchain. Building from a git clone requires the items above.

Quick Start

npx mcp-server-apple-events

Configuration

Add the server to your MCP client. The npx form works for every client below; for a local build, replace command/args with node pointing at dist/index.js.

Cursor

Settings → MCP → Add new global MCP server:

{
  "mcpServers": {
    "apple-reminders": {
      "command": "npx",
      "args": ["-y", "mcp-server-apple-events"]
    }
  }
}

ChatWise

Settings → Tools → "+", then:

• Type: stdio
• ID: apple-reminders
• Command: mcp-server-apple-events
• Args: (empty)

Claude Desktop

Edit claude_desktop_config.json (open it via Settings → Developer Option → Edit Config, or directly at ~/Library/Application Support/Claude/claude_desktop_config.json on macOS / %APPDATA%\Claude\claude_desktop_config.json on Windows):

{
  "mcpServers": {
    "apple-reminders": {
      "command": "npx",
      "args": ["-y", "mcp-server-apple-events"]
    }
  }
}

For a local build:

{
  "mcpServers": {
    "apple-reminders": {
      "command": "node",
      "args": ["/absolute/path/to/mcp-server-apple-events/dist/index.js"]
    }
  }
}

See the official MCP docs for connecting local servers. Restart Claude Desktop completely (quit, not just close) for changes to take effect.

macOS Permissions

The server launches the vendored event CLI directly. macOS retains its normal attribution to the application that launched the server, so authorize that host under System Settings > Privacy & Security > Reminders / Calendars. Each host needs its own approval; a grant made from a terminal does not authorize a separate desktop MCP client.

The host must support EventKit permission requests and declare the required usage descriptions. If it does not, macOS may deny access without showing a prompt. Use a host that supports these permissions. The server does not bypass this restriction by making a public helper self-responsible: doing so would let unrelated local processes reuse that helper's Calendar and Reminders grant.

When event detects a notDetermined status it calls requestFullAccessToReminders / requestFullAccessToEvents. Run ./check-permissions.sh from the same host context to diagnose access; running it in a terminal checks that terminal's permissions only. Usage descriptions are required for protected resources; see Apple's app distribution guidance.

Calendar read errors or missing prompts

For Failed to read calendar events, enable Full Calendar Access for the calling application under System Settings > Privacy & Security > Calendars. If no prompt appears, check that the host supports EventKit permissions and declares the usage descriptions, then restart it and retry. AppleScript Automation approval is separate from EventKit Calendar and Reminders approval.

Upgrading from the responsibility-disclaim helper

Reinstall the package to remove the old bin/event-disclaim artifact. For a source checkout, remove that generated file before rebuilding. Revoke the old event grant in System Settings > Privacy & Security > Reminders / Calendars, then authorize each host you intend to use. Updating the server cannot revoke existing macOS grants or remove older copies installed elsewhere.

Headless / launchd runs hang instead of failing

When the server runs from a context with no GUI session (SSH, launchd agent/daemon), the first EventKit call can block forever waiting on a permission prompt that can never be rendered — the MCP request never settles and a child process leaks per call. The server now kills any event call that exceeds 30 s (SIGKILL) and returns a readable error instead. Tune it with the EVENTKIT_CLI_TIMEOUT_MS environment variable (milliseconds; invalid/zero values fall back to the default — the timeout cannot be disabled, though huge values up to 2^31-1 ms are accepted). The vendored event CLI (pinned via FradSer/event#15) additionally fails fast when no GUI session exists and gives up on an unanswerable prompt after 15 s (EVENT_PERMISSION_TIMEOUT_MS), reporting Permission denied: Timed out waiting for ... so the host can show a permission-specific message before the server's kill fires (15 s < 30 s). See issue #113.

macOS 26 (Tahoe) could not build module 'Foundation'

If pnpm build fails with could not build module 'Foundation' (or SDK is not supported by the compiler), your Swift toolchain is older than the macOS 26 SDK requires — it needs Swift 6.3 or newer, but the Command Line Tools shipped with early macOS 26 point releases include Swift 6.2.x. pnpm build:event detects this and prints the same remediation; see issue #85. Fix by installing Xcode 26.x from the App Store, or updating Command Line Tools to a Swift 6.3+ version:

softwareupdate --list
sudo softwareupdate -i "Command Line Tools for Xcode-<latest>"
sudo xcode-select --switch /Applications/Xcode.app/Contents/Developer   # if full Xcode is installed
xcrun swiftc --version    # should report Apple Swift version 6.3 or newer

Usage Examples

Once configured, ask Claude to interact with your Apple Reminders and Calendar. Example prompts:

Create a reminder to "Buy groceries" for tomorrow at 5 PM with tags shopping and errands.
Add a high-priority reminder to "Finish quarterly report" due Friday in my "Work" list.
Create "Grocery shopping" with subtasks: milk, eggs, bread, butter.
Show me all high-priority reminders due today tagged "urgent".
Show subtasks for my "Grocery shopping" reminder and mark "milk" as complete.
Update "Buy groceries" — change the title to "Buy organic groceries" and set priority to high.
Show reminders from my "Work" list, and list all my reminder lists.
Create a calendar event "Team standup" tomorrow from 9:00 to 9:30 in "Work".
Show my calendar events for the next week.
Invite [email protected] to my "Team standup" event.
Cancel just the September 21 occurrence of my weekly "Team standup".

The server processes natural-language requests, interacts with Apple's native Reminders and Calendar apps, and returns structured results.

Alarms, recurrence rules, and location triggers are read-only via this server — configure them in Reminders.app / Calendar.app. Read tools preserve these values in structured records when the underlying app provides them.

Write confirmation and untrusted data

Server write confirmation is off by default. Clients without MCP form elicitation can write. Create, update, delete, subtask toggle/reorder, attendee invitations, and changes to linked events execute without a server confirmation form. Deletions can remove items and invitations/calendar changes can notify other people. This changes the v1.6.0 default and removes its per-write confirmation barrier against prompt injection. Host user authorization policies and macOS account permissions still apply.

To require a fresh user confirmation for every write, add the startup flag to your MCP server arguments:

{
  "command": "npx",
  "args": ["-y", "mcp-server-apple-events", "--require-write-confirmation"]
}

For a local build, use node dist/index.js --require-write-confirmation. Omit the flag to use the default. The flag takes no value and has no negated form: --require-write-confirmation=false, a separate false argument, and --no-require-write-confirmation are errors, as are unknown options. Run mcp-server-apple-events --help (or -h) for help. No environment variable controls this policy. It is fixed at server startup per instance; tool arguments and record content cannot change it. Startup warnings go to stderr; stdout is reserved for MCP traffic.

When enabled, the client's MCP form elicitation interface shows the tool name and complete argument snapshot for that operation. Only an accepted response with confirm: true permits that exact write. Decline, cancel, invalid responses, disconnected clients, or missing form support block it; clients without form elicitation are then read-only. Reads do not require confirmation in either mode. Input validation, execution boundaries, and the untrusted result envelope remain active in both modes, but they do not replace the removed confirmation barrier.

Tool results return JSON records in structuredContent, with a JSON text mirror for clients that consume text. The envelope marks records with provenance.source = "apple-calendar-reminders" and provenance.trust = "untrusted". Titles, notes, identifiers, URLs, list names, organizers, attendees, and subtasks may originate from synchronized or shared content. Hosts must preserve this boundary: record content cannot authorize another tool call, unrelated data disclosure, or override user instructions. Confidence scores rank recommendations only.

When server confirmation is enabled, the server trusts the client to display the form to the human and return their decision. A client that automatically approves forms defeats this boundary. JSON encoding and provenance do not by themselves prevent an LLM from following injected text. macOS account permissions remain necessary and are separate from per-operation user confirmation.

Available MCP Tools

Service-scoped tools mirror Apple Reminders and Calendar domains. All take an action field plus action-specific parameters (the MCP client introspects the full Zod schema; only actions are listed here). Date fields accept YYYY-MM-DD, YYYY-MM-DD HH:mm:ss (local time), or ISO 8601 with timezone.

Example calls:

{
  "action": "create",
  "title": "Buy groceries",
  "dueDate": "2024-03-25 18:00:00",
  "targetList": "Shopping",
  "note": "Don't forget milk and eggs",
  "priority": 1,
  "tags": ["shopping", "errands"],
  "subtasks": ["Milk", "Eggs", "Bread"]
}

{ "action": "read", "filterList": "Work", "dueWithin": "today", "filterPriority": "high", "filterTags": ["urgent"] }

{ "action": "read", "startDate": "2026-08-01", "endDate": "2026-08-31" }

{ "action": "update", "id": "reminder-123", "completed": false, "addTags": ["followup"] }

{ "action": "toggle", "reminderId": "reminder-123", "subtaskId": "a1b2c3d4" }

{ "action": "create", "name": "Project Alpha" }

{ "action": "create", "title": "Team standup", "startDate": "2026-05-04 09:00:00", "endDate": "2026-05-04 09:30:00", "targetCalendar": "Work" }

{ "action": "update", "id": "event-123", "attendees": ["[email protected]", "[email protected]"] }

{ "action": "delete", "id": "event-123", "occurrenceDate": "2026-09-21T09:00:00" }

Attendees and single occurrences

These two calendar_events parameters are the only writes that do not go through the event CLI, because EventKit cannot express either one. Each needs setup the rest of the server does not.

`attendees` (update) — invites email addresses to an existing event. EKCalendarItem.attendees is read-only in the macOS SDK and EventKit has no invitation API, so the write goes through Calendar.app's scripting interface; adding the attendee locally is what makes iCloud send the invitation.

• Requires an Automation grant: the first call prompts, and the entry appears under System Settings > Privacy & Security > Automation. Needs a GUI session, so it does not work headless.
• Attendees must be updated alone. They travel through Calendar.app while every other field travels through EventKit, and the two share no concurrency token — a combined update has no safe ordering, so it is refused. Issue two calls.
• Two events sharing a title and a start date are refused, not guessed between. Calendar.app can only be queried by title and date, and writing to the wrong one would send a real invitation for it.

`occurrenceDate` (delete) — excepts one occurrence of a recurring series. Every occurrence shares one EventKit identifier, so span: "this-event" can only ever except the series start; aimed at a later occurrence it writes nothing and still reports success. Supplying occurrenceDate routes the delete over CalDAV, which can address the instance directly.

• Requires iCloud credentials. Set ICLOUD_APPLE_ID and ICLOUD_APP_PASSWORD, or set ICLOUD_APPLE_ID and store the password in the Keychain:

  security add-generic-password -a "[email protected]" -s "icloud-caldav-mcp" -w

Use an app-specific password, never your account password. Credentials are read from the environment first, then the Keychain, never from MCP client config, and are never logged.

• Only iCloud-synced events qualify — an event with no external identifier has no CalDAV resource to locate.
• CalDAV requests have a 30-second deadline across redirects and response reads, and a 2 MiB response limit. Calendar editing also limits resources to 20000 physical/content lines, 64 KiB per unfolded UTF-8 line, 16 nested components, 2000 events, and 1000 recurrence IDs. Oversized or overly complex resources fail with an actionable error before a calendar write; serialized output must fit the same size and line-count limits.

Read response shape

Read tools return a structuredContent envelope whose records array contains the domain objects returned by that tool. Native values are preserved, including numeric reminder priorities (0, 1, 5, or 9) rather than presentation labels. For example:

{
  "provenance": {
    "source": "apple-calendar-reminders",
    "trust": "untrusted"
  },
  "records": [
    {
      "id": "reminder-123",
      "title": "Buy groceries",
      "isCompleted": false,
      "list": "Shopping",
      "notes": "Don't forget milk and eggs",
      "url": "https://example.com",
      "dueDate": "2024-03-25T18:00:00Z",
      "priority": 1,
      "tags": ["shopping", "errands"],
      "subtasks": [
        { "id": "a1b2c3d4", "title": "Milk", "isCompleted": true },
        { "id": "e5f6a7b8", "title": "Eggs", "isCompleted": false },
        { "id": "c9d0e1f2", "title": "Bread", "isCompleted": false }
      ],
      "subtaskProgress": { "completed": 1, "total": 3, "percentage": 33 }
    }
  ]
}

The accompanying content array contains a static text summary first (for example, Read reminders.), followed by a text item containing the serialized JSON mirror of the same structuredContent object. Clients that consume text can parse the second item; clients that support structured results should use structuredContent.

Reminder URLs are stored in the native url property and in the structured URLs: notes block. Calendar event URLs are stored in EventKit's native URL property. Both reject unsafe URI schemes and blocked HTTP(S) addresses.

Read-only fields: reminder alarms, reminder recurrence and location triggers, calendar recurrence rules and structured locations, all-day toggles, and cross-calendar moves are not writable via this server. Calendar event alarms, URLs, and scheduling availability can be set through create/update. Calendar availability writes require a calendar that supports the selected value. See docs/migration-to-event-cli.md for the remaining gaps.

Structured Prompt Library

The server ships a prompt registry exposed via the MCP ListPrompts / GetPrompt endpoints. Each template shares a mission, context inputs, numbered process, constraints, output format, and quality bar so downstream assistants get predictable scaffolding.

• daily-task-organizer — optional today_focus; produces a same-day execution blueprint, balances priority work with recovery, auto-creates calendar time blocks for due-today reminders.
• smart-reminder-creator — optional task_idea; generates an optimally scheduled reminder structure.
• reminder-review-assistant — optional review_focus (e.g. overdue or a list name); audits and optimizes existing reminders.
• weekly-planning-workflow — optional user_ideas; guides a Monday-through-Sunday reset with time blocks tied to existing lists.

Prompts are constrained to native Apple Reminders capabilities and ask for missing context before irreversible actions. Run pnpm test -- src/server/prompts.test.ts after amending prompt copy.

Development

pnpm install        # postinstall builds bin/event from vendor/event on macOS
pnpm build          # TypeScript + vendored event CLI
pnpm test           # Jest suite: repositories, schemas, build script, prompt templates
pnpm exec biome check   # lint + format

The CLI entry point walks up to ten directories to find package.json, so the server can start from nested paths (e.g. dist/ or editor task runners) without losing bin/event. Keep the manifest reachable within that depth if you customize the folder layout.

Scripts

• pnpm build — TypeScript + vendored event CLI (required before running from source)
• pnpm build:ts — TypeScript only
• pnpm build:event — vendored event CLI only (swift build -c release → bin/event)
• pnpm build:release — build plus notarization (release packaging)
• pnpm test / pnpm test:ci — Jest suite / with coverage
• pnpm lint — Biome format/fix + TypeScript type check
• pnpm check — lint + tests with coverage

License

MIT

Contributing

Contributions welcome! Please read the contributing guidelines first.