Kelly

Your calendar in Claude's context — a local MCP server for CalDAV.

Status: working prototype

What it does

Kelly gives Claude read access to your CalDAV calendar so it can help you plan your day, check for conflicts, summarize your week, or answer questions about your schedule — without you copy-pasting events.

• Runs locally on your machine — credentials never leave your device
• Stores credentials securely in macOS Keychain
• Read-only — Kelly can't create, modify, or delete events

Architecture

┌─────────────────────────────────────────────────────┐
│  Your machine                                       │
│                                                     │
│  ┌──────────────┐   stdio   ┌──────────────────┐   │
│  │ Claude       │◄─────────►│ kelly            │   │
│  │ Desktop/Code │           │ (MCP server)     │   │
│  └──────────────┘           └────────┬─────────┘   │
│                                      │              │
│                              macOS Keychain         │
│                              (credentials)          │
└──────────────────────────────┼──────────────────────┘
                               │ HTTPS (Digest auth)
                               ▼
                     ┌───────────────────┐
                     │ CalDAV server     │
                     │ (Pixel/SabreDAV)  │
                     └───────────────────┘

Quick Start

Prerequisites

• Python 3.10+
• uv (Python package manager)

Install

git clone <this-repo>
cd kelly
uv sync

Store credentials

kelly setup

You'll be prompted for your CalDAV principal URL, username, and password. These are stored in macOS Keychain — not in any file.

Add to Claude Desktop

Add this to your Claude Desktop MCP config (~/Library/Application Support/Claude/claude_desktop_config.json):

{
  "mcpServers": {
    "kelly": {
      "command": "uv",
      "args": ["run", "--directory", "/path/to/kelly", "kelly", "serve"]
    }
  }
}

Add to Claude Code

claude mcp add kelly -- uv run --directory /path/to/kelly kelly serve

Verify

Ask Claude: "Check my calendar connection" — it should call the check_connection tool and report success.

Available Tools

Tool	Description
check_connection	Verify CalDAV credentials and server connectivity
list_calendars	List available calendars under your principal
list_upcoming_events	Fetch events for the next N days, optionally filtered by calendar name

Security Model

Aspect	Detail
Credential storage	macOS Keychain (primary), env vars (fallback for CI/Docker)
Transport	stdio only — no network listener, no exposed ports
Scope	Read-only — no calendar mutations possible
Network	Outbound HTTPS to your CalDAV server only
Dependencies	Minimal: requests, icalendar, fastmcp, keyring

Environment variable fallback

If you can't use Keychain (CI, Docker, Linux), set these instead:

export CALDAV_PRINCIPAL_URL="https://caldav.example.com/principals/you/"
export CALDAV_USER="your-username"
export CALDAV_PASS="your-password"

Development

Run tests

uv run pytest

Project structure

kelly/
├── __init__.py        # Package version
├── cli.py             # CLI: kelly setup | kelly serve
├── server.py          # FastMCP server + tool definitions
├── caldav.py          # CalDAV protocol (PROPFIND, REPORT, iCal parsing)
└── credentials.py     # Keychain/env credential loading
tests/
├── test_caldav.py     # CalDAV logic tests (mocked HTTP)
├── test_server.py     # MCP tool tests
└── test_credentials.py # Credential fallback tests