Nico Apple MCP

Nico Apple MCP is a local MCP server. It connects Claude Code, Codex, Claude Desktop, or any other MCP client to the Calendar, Notes, and Contacts apps already on your Mac. The server runs on your Mac and makes no network calls of its own, and there's no account or API key.

Why this one

• It changes the event you meant. Every event, note, and contact comes back with an ID, and edits use it. When two items share a name, such as five events called "Lunch", it refuses to guess and asks for the ID.

• Repeating meetings are safe. Moving this week's stand-up moves this week's stand-up, not the whole series.

• Calendar goes straight to macOS. A small signed helper app uses Apple's own calendar framework, EventKit, instead of scripting the Calendar app, so it's fast and never opens Calendar on your screen.

• It previews before it writes. Every tool that creates, changes, or deletes something takes dryRun: true to show what would happen first.

• It's quick. Measured on a Mac mini:

  Task	Time
  A month of calendar events	0.07 s
  List 227 notes	0.2 s
  List 335 contacts	1.5 s
  Brief a day of meetings	0.6 s

• It tells you what's wrong. doctor checks every permission and dependency in one go.

Related MCP server: calendar-app-mcp

Meeting prep

Ask your assistant to prep me for tomorrow. meeting_prep reads the day's meetings, looks up every attendee in Contacts by email or name, and flags anyone you don't have saved yet:

Thursday, 29 October 2026: 3 events

09:30–10:15  Q4 rate review
Calendar: Work · Where: Zoom
• Priya Shah, Head of Procurement at Harbourline · priya.shah@harbourline.example · +852 5550 1234
• Tom Becker · tom@harbourline.example · not in Contacts
Agenda: Go through the November quote and the new Rotterdam surcharge.

12:00–12:45  Coffee with Mei
Calendar: Personal · Where: Blue Bottle, Central
• Mei Lin (organizer) · mei@lin.example · +852 5550 8899

15:00–16:00  Warehouse walkthrough
Calendar: Work · Where: Kwai Chung Terminal 4
• Daniel Okafor, Operations Director at Kestrel Foods · d.okafor@kestrelfoods.example
• Sam Wu (declined) · sam.wu@kestrelfoods.example · not in Contacts

Not in Contacts yet: Tom Becker <tom@harbourline.example>, Sam Wu <sam.wu@kestrelfoods.example>

With saveNote: true the brief is also saved to Apple Notes, so it's on your phone when you walk in.

Things you can ask

• "What's on tomorrow, and who am I meeting?"

• "Prep me for Thursday and save it to Notes."

• "Add everyone from tomorrow's meetings who isn't in my contacts."

• "Move this week's 1:1 with Priya to 4pm. Just this week."

• "Find my note about the Shenzhen trip and add today's update to it."

• "Delete the test event I made earlier. Show me first."

Tools

Install

You need macOS 14 or newer, Bun, and Xcode's command line tools (xcode-select --install).

git clone https://github.com/proxynico/nico-apple-mcp.git
cd nico-apple-mcp
bun install
bun run build:swift

bun run build:swift builds and signs the small NicoAppleMCPCalendarHelper app that macOS grants Calendar access to.

Then register it with your assistant, using the full path to your clone.

Claude Code

claude mcp add --scope user nico-apple-mcp -- bun run /path/to/nico-apple-mcp/src/index.ts

Codex

codex mcp add nico-apple-mcp -- bun run /path/to/nico-apple-mcp/src/index.ts

Claude Desktop and other clients

{
  "mcpServers": {
    "nico-apple-mcp": {
      "command": "bun",
      "args": ["run", "/path/to/nico-apple-mcp/src/index.ts"]
    }
  }
}

Restart the assistant after registering or updating.

Permissions

macOS asks before anything can read your Calendar, Notes, or Contacts, and this server can't get around that.

1. Ask your assistant to run doctor.

2. Ask it to run calendar_list_calendars, and approve the Calendar prompt.

3. Approve the Notes and Contacts prompts the first time those tools run.

If a prompt never appears:

• Calendar: System Settings > Privacy & Security > Calendars, and give NicoAppleMCPCalendarHelper Full Access.

• Notes and Contacts: System Settings > Privacy & Security > Automation, and allow your assistant or terminal app to control Notes and Contacts.

A healthy doctor looks like this:

OK bun
OK osascript
OK Notes automation
OK Contacts automation
OK calendar helper
calendar authorization: authorized
OK calendar permission: granted

Working with records

Search results include an eventId, noteId, or contactId. Pass it back to update, move, or delete exactly that item. Exact titles and names still work, but a name that matches more than one item is refused.

Every occurrence of a repeating event shares one eventId. To change one occurrence, also pass windowStart and windowEnd around it. An eventId alone for a repeating event is refused rather than guessed.

Dates are ISO 8601. A date without a time means local midnight on your Mac.

2026-05-12
2026-05-12T10:30:00
2026-05-12T10:30:00+08:00

Troubleshooting

Run doctor first.

• Calendar says notDetermined or denied: run calendar_list_calendars, approve the prompt, check the Calendars privacy setting above, and restart the assistant.

• Notes or Contacts fail: check the Automation privacy setting for the app running the server, and restart the assistant.

• doctor says the calendar helper is older than its source: run bun run build:swift, approve the Calendar prompt again (macOS treats each build as a new app), and restart the assistant.

• Tools are missing or behave like an old version: quit old assistant sessions and start a new one so the server reloads.

How it works

One local MCP server written in TypeScript on Bun. Calendar runs through a signed Swift helper app because macOS grants Calendar access to apps, not to background scripts. Notes and Contacts use Apple's scripting interface, reading whole lists in one request instead of item by item.

Development

bun install
bun run build:swift
bun run test        # type check and tests
bun run src/index.ts

Before sending a change, also run doctor and a quick create, update, and delete on the apps you touched.

License

MIT