Cupertino

Put your agent to work in your everyday Apple apps.

MCP servers for the Apple apps already on your Mac, and the signed app that grants them their permissions once instead of once each — for any agent that speaks MCP, not for one host.

Unofficial. Not affiliated with Apple. These drive the apps that are already on your Mac.

In use

Look at how I write in my work inbox, then draft this reply in the same voice.

Pull together everything about the Atlas launch from my mail, my notes and my calendar. What do I still owe people?

Turn the action items from yesterday's client thread into reminders, due Friday.

Every one of those carries a constraint — an account, a date bound, a filter. That is the part the naive osascript path answers in 74 seconds or answers wrongly, and the reason a server earns its place: it holds what the model would otherwise re-derive every session. The measurements are in docs/verify.md; what the alternatives cost is in docs/alternatives.md.

The last one needs the write gate open on Reminders. Writes are off per surface until you turn them on, and the toggle decides whether the mutating tools are registered at all — an agent with writes off cannot see that they exist.

Surfaces

Screen, Sound, Desktop and Simulator arrive switched off. Every other surface that brokers an Apple app is on when Cupertino is installed; those four are not, because Screen Recording, the microphone and Accessibility are per-process grants that reach past the surface being brokered. Desktop reaches furthest — Accessibility does not scope to a target at all, so the right to press a button in Maps is the right to press one in anything, and it additionally arrives with writes off, so it can only look until you say otherwise. Simulator holds the same grant and pins its own reach to Simulator.app, with no switch that widens it. Switch them on in the surface list if you want them.

Each surface is its own server, so a host loads only the tools it wants. Every surface that brokers an Apple app through its store or its scripting dictionary is also its own npm package; screen, sound, desktop and simulator are not, and could not be — the first three broker a framework rather than an app, simulator brokers an app through Accessibility, and in every case the grant lives in the app, so the app serves them in-process and a published package could do nothing. See docs/screen.md, docs/desktop.md and docs/simulator.md.

simulator is the lane for an app you are building. Simulator.app bridges the simulated device's accessibility tree into the Mac's, so an iOS app's own controls are readable and pressable here with no WebDriverAgent and no runner process — and the surface answers in iOS points, the space ios_simulator_tap and ios_simulator_screenshot use, with the window scale measured on every call rather than assumed. It reads, finds and presses; behind writes it taps, swipes, types and presses the device's buttons. Booting, installing, launching, screenshots and push need no grant and stay with @mgcrea/mcp-ios-simulator, which this complements rather than copies.

desktop is the one surface that drives an interface rather than reading a store, and it does it through AXUIElement natively rather than through osascript. That distinction is the whole surface: every Accessibility measurement this project took before 2026-09-05 went through System Events, one Apple Event per attribute, which is where "33.6 ms a round trip" and "~14 s for a place card" came from. Natively the same walks cost 1.24 ms a round trip and the same place card 0.177 s. The transport was the cost, not the API — see docs/desktop.md.

They share one bundle and one Full Disk Access grant, which is the whole reason they live together — see docs/distribution.md.

Quick start

Every server that brokers an Apple app is on npm and runs straight from npx — for Claude Code, a .mcp.json beside your project:

{
  "mcpServers": {
    "apple-mail": {
      "command": "npx",
      "args": ["-y", "@mgcrea/mcp-apple-mail"]
    },
    "apple-notes": {
      "command": "npx",
      "args": ["-y", "@mgcrea/mcp-apple-notes"]
    }
  }
}

The packages are MIT and need no licence key. What they do need is a permission, and on npm you grant it to whatever launches them — your editor, your terminal — which is the trade the signed Cupertino.app exists to avoid: one Full Disk Access grant held by a notarized binary, instead of one per host. See docs/licensing.md.

brew install --cask mgcrea/tap/cupertino

Or run them from source:

git clone https://github.com/mgcrea/cupertino.git
cd cupertino
pnpm install
pnpm build

then point your host at packages/<surface>/dist/cli.js by absolute path.

Writes are off unless you ask for them — see Configuration.

Running through the menu bar app instead routes every server through the bridge, so Full Disk Access is granted to Cupertino rather than to whichever editor spawned the server:

make run      # build Cupertino.app, point it at packages/*/dist, launch it
make smoke    # handshake every server through the bridge

make surfaces writes a gitignored .mcp.json at the repo root, wired for that path — it is a developer's local working config rather than something to commit, because every entry is an absolute path into one Mac's bundle. make on its own lists every target.

Note the different server names. Wired by hand as above, a server is apple-mail and runs under whatever grant its host process has. Wired by Cupertino it is cupertino-mail, because that entry points at the app's bridge and runs under the app's grant. Two names for two deployments, and you can have both. The app only ever touches its own cupertino-* keys — an apple-mail entry belonging to some other server is left alone.

Cupertino is machine configuration, not a project dependency, so it belongs in a per-user config: one file each, and the equivalent of --scope user everywhere. Deliberately not --scope project, which writes an .mcp.json meant to be committed — that entry is an absolute path into a bundle on one Mac, backed by one person's Full Disk Access grant, and it would be useless to a teammate and unwise to offer them.

All seven are written by the app, and nothing has to be pasted into a terminal. Six keep strict JSON and are merged into as dictionaries — five under mcpServers, Visual Studio Code under servers in User/mcp.json, which is a different file from the JSONC settings.json it was confused with for two releases. The seventh, ~/.codex/config.toml, is TOML full of hand-written prose and structure, so it is never re-serialised: ClientWiringTOML replaces the lines that hold MCP servers and quotes every other byte verbatim. ChatGPT has no row of its own because it is not a separate client — the ChatGPT app, the Codex CLI and the Codex IDE extension all read that same file, which is the row called "ChatGPT & Codex".

Claude Code's ~/.claude.json is written directly, and it is the one config where that deserves a paragraph: it holds this machine's credentials beside ninety-odd project blocks, and Claude Code writes to it while it runs. So every write copies the file to ~/.claude.json.cupertino-backup first, lands through a temp file and an atomic swap, and is refused outright if anything touched the file between the read and the swap — in which case the app re-reads and merges again. What no writer can promise is the last word: a session holding its own copy of the file will win, and claude mcp add is the same read-modify-write from another process, which is why handing over that line was never the safer option. The difference is that the app reads the file it wrote, so a clobbered entry shows up as Not configured the next time you open Settings, with a button that fixes it.

This repo's own gitignored .mcp.json is the exception, and it names its servers cupertino-*-dev on purpose: it points at apps/apple/.build, so working on the app means having the development build and the installed one side by side. Claude Code reports servers of the same name in two scopes as a conflict rather than picking one, so the suffix is what keeps both usable.

Cupertino.app needs macOS 26 or later — its icon is an Icon Composer bundle, which nothing older can render. The servers themselves are plain Node and carry no such floor; only the menu bar app does.

Permissions

These land on whatever process launched the server — your editor, your terminal, or Cupertino — never on Mail, Notes or Reminders themselves.

The last three are why Screen, Sound, Desktop and Simulator arrive switched off: each is a per-process grant that reaches past the surface being brokered, and Accessibility does not scope to a target app at all — Simulator pins its own reach in the server, since the system will not.

System Settings → Privacy & Security → Full Disk Access → add the launching app, then restart it. Granting it to Mail.app does nothing; the reader needs the permission, not Mail.

What works without Full Disk Access:

Tools that need the index don't disappear when it's missing — the tool list is a pure function of allowWrites and nothing else, because MCP clients cache it. They return a structured degraded result naming what's absent. apple_mail_diagnostics / apple_notes_diagnostics report which lane is live and how to grant what's missing.

Tools

Read tools are always registered. Write tools are invisible unless writes are enabled — not merely refused.

Mail

Notes

Reminders

Calendar

list_events expands repeating events, so a weekly standup is returned once per week. Every result carries the window the expansion is known to cover, and sets truncated when a range runs past it rather than coming back short — a short list of events is indistinguishable from a free afternoon.

Contacts

resolve_handles turns phone numbers and email addresses into names, which is what makes the Messages surface readable at all. Read status on each result rather than assuming a name came back: unknown is common and not an error, and ambiguous means two contacts share the number, so no name is returned rather than a guess.

There is no delete tool. Contacts' scripting dictionary has no delete command of any kind, and this surface's writes go through Apple Events because its store is read-only by policy. That was true of every surface until Maps, which has no scripting dictionary to go through and writes SQL instead. See docs/contacts.md.

Messages

find_codes is registered too, behind its own APPLE_MESSAGES_ALLOW_CODES rather than the write gate — reading a one-time code is a read, and it is separated because it is the one read that hands over a credential.

One write tool, because the dictionary has one usable command. sdef lists send, login and logout; the other two would sign the user out of iMessage on every device they own. There is no edit, delete, mark-as-read or reaction verb to expose.

This is the only surface where Apple Events is a write lane and nothing else — every read through it fails, so with APPLE_MESSAGES_ALLOW_WRITES off no Apple Event is ever sent and no Automation grant is ever requested.

send_message prefers a chatRef from list_chats over a raw handle, because Messages refuses to enumerate participants for a script: an existing conversation is the only target that can be addressed reliably. Apple Events hands back no identifier for what it sent, so the result is reconciled against chat.db — reconciliation: "matched" carries a real message ref, and "pending" means Messages accepted the send but has not written the row yet. Pending is not a failure, and retrying it sends the message twice.

About 3% of messages across all history keep their text only in an archived NSArchiver blob that SQL cannot reach — and Apple stopped writing the plain column in early 2026, so for anything recent it is ~100%. This server decodes them; textSource on every result says which lane answered. See docs/messages.md.

Safari

The widest write set here, and it splits across two lanes that share nothing but the flag. open_url and add_reading_list_item are Apple Events that move a real, visible browser. click, fill and scroll act inside a page through the bundled Safari extension, which Safari consents to one website at a time — so their real gate is a per-site grant the user can see and revoke, and the write flag is the second lock rather than the only one. find_codes is registered separately behind APPLE_SAFARI_ALLOW_CODES, because reading a one-time code is a read.

There is deliberately no do JavaScript tool: it needs a developer-menu toggle that is not a TCC grant and whose state cannot be read, so diagnostics could never say in advance whether it would work.

list_tabs needs no Full Disk Access — it needs an Automation grant instead, and Safari has to be running. Ask for the tab marked frontmost to get the one the user is looking at: active means selected in its own window, so two open windows produce two active tabs. A tab's history field being null means not found in history, never "never visited": the match rate is a property of the tab set rather than of the surface, measured at 60.7%, 55.3% and 8.3% on three real runs. Single-page apps are the main reason — a page reached by pushState commits no history row at all. Each match reports historyMatch, and even an exact one can be a different site when the address is reused, as any localhost URL is.

Page content comes from a Safari extension, and only for websites you allow it on. apple_safari_read_page returns a page as readable text or raw HTML. It is a snapshot taken when the page loaded rather than a live read, so every result says when it was captured and how old it is — a page you have navigated away from still answers, and saying so is the point.

There is still no do JavaScript tool. That verb needs "Allow JavaScript from Apple Events", a developer-menu toggle which is not a TCC grant and whose own state cannot be read, so diagnostics could never tell you in advance whether it would work — and it is global: any process able to send Apple Events could then run script in any tab. Safari exposes no AXWebArea for page content either, so the Accessibility lane that reaches Mail's composer does not reach a web page. The extension is the only route, and it is the one Safari scopes per website. See docs/safari.md.

Maps

Favourites, collections (Guides) and recents, from a Core Data store under Full Disk Access — with real coordinates and addresses, which is what makes it worth having.

list_unfiled_places returns the saved places filed in no Guide. Maps shows them only in a union view, and 7 of the 12 on the probed Mac appeared nowhere else in the store — not as a favourite, not in another Guide, not in recents.

It reads what is saved on this Mac. It does not search Apple's map of the world, geocode an address, or give directions; the guide says so, because answering those from general knowledge is the most likely way for this surface to be wrong.

It writes, and it is the only surface here that does so without an Apple Event. Maps ships no scripting dictionary and registers no App Intents on macOS, so add_favorite and remove_favorite go into the Core Data store directly — which means usesAppleEvents stays false even with the write gate open, and adding this surface still widens no Automation consent.

The part that cannot be faked is the GEO place record, so it never is: the place is opened through the maps:// URL scheme, Maps mints the record itself, and it is copied. Two consequences the tools state rather than hide — saving a place the store does not already know leaves an entry in Recents, and because the store is mirrored by NSPersistentCloudKitContainer the write reaches every device on the account. There is no local-only insert here.

It was also declared impossible three times before it was found: the store has no file extension, it sits in the one directory of Maps' container that Full Disk Access gates, and group.com.apple.Maps is a decoy that is EPERM rather than empty. See docs/maps.md.

All names are prefixed apple_mail_ / apple_notes_ / apple_reminders_ / apple_calendar_ / apple_contacts_ / apple_messages_ / apple_safari_ / apple_maps_ — and apple_screen_ / apple_sound_ / apple_desktop_ / apple_simulator_ for the surfaces the app serves itself.

Prompts and resources

Tools are what an agent calls. Two other things every server knows are the wrong shape for a tool, because a tool result is not addressable and does not outlive the session that paid for it: the inventory every other tool takes as an argument, and the diagnostics that get read one round trip after the confusing answer instead of before it.

So each server also exposes resources:

and workflow prompts, which hold the constraints a tool description cannot: not "what this call does" but what order the calls go in. apple_mail_triage, apple_mail_find_thread, apple_reminders_whats_due, apple_calendar_whats_my_day, apple_messages_catch_up and the rest, one to three per surface. Each embeds its surface guide, so a host that expands a prompt hands the model the reference material with it.

Write prompts follow the write tools exactly: with writes off, apple_mail_draft_reply is not refused, it is not registered. Full design notes, and what was deliberately left out, in docs/prompts-and-resources.md.

Configuration

Environment only — these servers hold no secret of their own, so there is no config file. Prefix is APPLE_MAIL_, APPLE_NOTES_, APPLE_REMINDERS_, APPLE_CALENDAR_, APPLE_CONTACTS_, APPLE_MESSAGES_, APPLE_SAFARI_ or APPLE_MAPS_.

allowWrites gates mutation, but on Mail the larger blast radius is reading an entire archive — that is what *_ACCOUNTS is for, and it is enforced in exactly one place so no query path escapes it. Mail also takes *_ROOT, *_ENVELOPE_INDEX, *_DEGRADED_MAX_MESSAGES, *_BODY_MAX_BYTES, *_BODY_SCAN_MAX, *_BODY_SCAN_BYTES and *_MAILBOX_CACHE_TTL_MS; see packages/mail/src/config.ts.

*_EXPOSE_PROMPTS is a cost knob, not a safety gate — which is why it defaults on while writes default off. Measured across all eight node servers with writes enabled, the prompt and resource listings come to ~3.7k tokens against ~25.3k for the tool definitions, so about 14% on top of a bill that tools dominate either way; resource contents cost nothing until something reads one. The per-surface breakdown is in docs/prompts-and-resources.md.

*_LAZY_TOOLS is the knob for that ~25.3k. With it on, a server lists its diagnostics tool plus apple_<surface>_search_tools, _describe_tool and _call_tool — and _call_write_tool when writes are on — instead of every tool up front: ~5.8k tokens across the eight servers rather than ~25.3k, a 4.4× cut. It is off by default because it trades rather than tightens. The server refuses exactly what it refused before, and a write tool is still absent rather than merely hidden when *_ALLOW_WRITES is off, but your client's per-tool permission prompt collapses into two: one for this surface's reads, one for its writes. Leave it off for Claude Code and Claude Desktop, which already fetch tool schemas only when a task needs them and so pay the cost for nothing.

Calendar takes APPLE_CALENDAR_WORKDAY_START, APPLE_CALENDAR_WORKDAY_END and APPLE_CALENDAR_WORKDAYS (mon,tue,wed,thu,fri), which set the working day apple_calendar_find_availability offers time inside when a call names no hours of its own.

The app

The menu bar is Cupertino's whole surface — there is no Dock icon and no main window.

The Activity window records tool names and the arguments each was called with. Message contents — a mail body, a message, a note's text — are blanked unless you turn them on for that surface, and results are recorded only for a surface that asks. Nothing is written to disk unless you ask for it: by default the log is a bounded ring in memory, cleared when Cupertino quits.

Settings › Activity turns on a durable audit log: append-only JSONL under Application Support, 0600, in segments, with retention by age and size. Whether that file carries arguments is a second switch, and whether it carries message contents is a third — getting a mail body onto disk takes three deliberate acts, because that is what it is.

Each record carries a hash of the one before it, so an edited field, a removed record or a truncated file can be detected. That is the whole claim: it catches tampering by something that does not know it is a chain. It is not proof against anyone who can write the file, because they can recompute it. Export writes the segments plus a manifest; signing is optional, proves the export came from this Mac unaltered, and means nothing to a recipient who was not given the key some other way. It is the answer to "what did the assistant just do with my mail?", and the reason the servers run under an app you can see rather than inside whichever editor spawned them.

Writes are off per surface until you turn them on, and the toggle decides whether the mutating tools are registered at all — an assistant with writes off cannot see that they exist.

Surfaces themselves can be switched off, from the switch in a surface's own pane or by right-clicking its row in the sidebar. A surface that is off is not served at all: its server key is left out of the clients Cupertino configures and pruned from the ones it has already written, its running servers are stopped, and the bridge refuses the connection if an older config still asks for it. That is the lever for the tool definitions you never use — eight servers wired everywhere is a cost every session pays. Clients configured before the change keep the entry until you press Update in that client's own pane, which names the surfaces it still holds — and the dot beside it in the sidebar turns amber until you do. The same button prunes the entry from every client, including the TOML one.

Everything that is true of one surface lives in that surface's pane: whether it is on, its Automation grant, its writes toggle, its store, and what its server actually exposes. Everything true of one client lives in that client's pane, the same way — the file, the entries, and what else is in it. Settings keeps only what belongs to neither: Full Disk Access, Accessibility and System Events, the audit log, updates and the licence.

Why a single app

Full Disk Access is one indivisible whole-disk grant. Granting it per surface buys no containment and costs a System Settings trip each time, so every surface ships inside one signed, notarized app called Cupertino. docs/distribution.md also records why the Mac App Store cannot host any of this, so the question does not get re-opened.

But the grant is not the only thing the app holds, and it is not the only reason to run the servers under it rather than under an editor:

docs/alternatives.md is the honest version of that list: what else reads Apple Mail for an assistant, and where those tools are ahead.

Documentation

Working on it

pnpm build          # every package
pnpm test           # every package
pnpm typecheck
pnpm lint
pnpm format

The marketing site is its own workspace, and deploys by hand:

pnpm --filter @mgcrea/cupertino-website dev     # astro dev
pnpm --filter @mgcrea/cupertino-website build   # static build

It is built from the design canvas in .idea/design/, and reads its tool counts from packages/*/src/tools/ rather than from this file — see apps/website.

The Swift half is xcodebuild, named by the Makefile rather than wrapped by it:

make app            # build Cupertino.app (Debug)
make run            # build, point at packages/*/dist, launch
make smoke          # handshake every server through the bridge
make stop           # quit and remove the socket

The app's screenshots are captured rather than taken by hand — apps/apple/Screenshots/ holds the config and the committed goldens, and the website renders the output:

make screenshots          # capture, gate against the goldens, compose both sets
make screenshots-check     # gate only — fails if the UI drifted
make screenshots-update    # accept the captures as the new goldens (review the diffs first)
make screenshots-selftest  # prove the gate fails when it should

A run takes over the pointer and the active app at the moment of each shot, so do not use the machine while it runs. It needs Screen Recording permission for the terminal, never for Cupertino itself. make screenshots-doctor checks that and the two other things that otherwise fail silently: whether the caption font resolves, and whether the output size is one a store would accept.

What the screenshots show is fixture data from apps/apple/Cupertino/DemoSeed.swift, not this Mac: in -ScreenshotMode the app starts no host, seeds its own log and sessions, and answers the permission and store questions from a table. Without that the images would report one laptop's TCC state and print its home directory into the marketing site.

Phase-0 probes are repo-wide and read-only. They need the permission of the surface they measure, and redact their output to counts, timings and DDL:

pnpm probe:mail      # Envelope Index — needs Full Disk Access
pnpm probe:mail-body # which lane can search message bodies — needs Full Disk Access
pnpm probe:notes     # Notes — the Apple Events half runs without it
pnpm probe:reminders # Reminders — the store path is a glob, so finding it is itself privileged
pnpm probe:messages  # chat.db — no Apple Events read lane exists, so this one needs the grant
                     #   --send-target=<handle> also checks the send lane's targeting, without sending
pnpm probe:calendar  # settles whether Calendar has a file lane at all
pnpm probe:safari    # History.db, and the Reading List hiding inside Bookmarks.plist
pnpm probe:maps      # MapsSync, the store with no file extension behind the grant
pnpm probe:contacts  # the resolver Messages needs — its own TCC grant, not Full Disk Access
pnpm probe:screen    # ScreenCaptureKit — Screen Recording, and it takes effect on relaunch

Every probed surface has a package except screen, sound and desktop, which the app serves in-process because their grants live in the app rather than in a package. Safari's write set is the widest here, and it splits across two lanes that share nothing but the flag: open_url and add_reading_list_item are Apple Events that move a real, visible browser, while click, fill and scroll act inside a page through the bundled Safari extension, which Safari consents to one website at a time — so their real gate is a per-site grant you can see and revoke, and the write flag is the second lock rather than the only one. find_codes sits behind its own APPLE_SAFARI_ALLOW_CODES rather than the write gate, because reading a 2FA code is a read; and there is deliberately no do JavaScript tool, because it needs a developer-menu toggle whose state cannot be read, so diagnostics could never say in advance whether it would work. See docs/safari.md. Maps writes to a store without an Apple Event at all, which no other surface does: it has no scripting dictionary, so add_favorite asks Maps to mint a place record through the maps:// URL scheme and then writes SQL into the Core Data store. That store is CloudKit-mirrored, so the write reaches every device on the account — the only write in the bundle whose blast radius exceeds the machine. docs/maps.md carries the four lanes that were measured to get there. Messages registers exactly one write tool, send_message, which is the whole of what its scripting dictionary can do. Every probe degrades rather than exits — an app that is not running, or a permission that is not granted, is reported as a finding — and none of them launches an app unless you pass --launch. Their shared mechanism lives in scripts/lib/probe-kit.mjs.

Releases are tagged per package, so a tag names what it publishes: mail-v1.20.0, reminders-v1.20.0, calendar-v1.20.0, core-v1.20.0. The app is tagged app-v1.20.0 and releases on its own lane — a signed, notarized Cupertino.zip attached to the GitHub release, plus its SHA-256. See docs/distribution.md.

The repo is cupertino; the npm packages stay @mgcrea/mcp-apple-*, because that is what people search npm for. Neither name is load-bearing. The bundle identifier io.mgcrea.cupertino is the string that actually matters, because changing it would invalidate every user's Full Disk Access grant.

Licence

Two, because the halves are not the same thing.

Cupertino asks for Full Disk Access, so the source stays readable — that is what such a grant is owed, and reading it is the point. Running it is a separate question: the licence check lives in the source, so any build asks for a key, yours or ours. What is sold is the notarized binary and the maintenance behind it. The servers are MIT and run on their own with no key at all. The reasoning is in docs/licensing.md.