MCP iCal Server

What is MCP iCal Server?

MCP iCal Server is an MCP (Model Context Protocol) server that enables AI agents to manage macOS calendars using natural language. It integrates with the macOS Calendar app and uses the OpenAI Agent SDK to provide a single, agent-powered entry point for all calendar operations. It is designed for users of MCP-compatible clients like Claude for Desktop who want to create, query, and update calendar events conversationally.

How to use MCP iCal Server?

Install the server with uv sync, then configure your MCP client (e.g., Claude for Desktop) by adding the server to claude_desktop_config.json with your OPENAI_API_KEY as an environment variable. Launch Claude from the terminal to trigger macOS calendar permissions. Once set up, invoke the single MCP tool send_to_calendar_agent with natural language requests like “What’s my schedule for next week?” or “Add a lunch meeting with Sarah tomorrow at noon.”

Key features of MCP iCal Server

• Single MCP tool (send_to_calendar_agent) for all operations
• Stateful conversations that maintain context between requests
• Natural language event creation with location, notes, and reminders
• Smart schedule queries and availability checking
• Intelligent event updates (time, date, calendar, notes)
• Multi-calendar support, including Google Calendar via iCloud sync

Use cases of MCP iCal Server

• Schedule meetings and appointments using natural language
• Check your availability for a given time window
• Modify existing events (reschedule, move to another calendar)
• View and manage events across multiple macOS calendars

FAQ from MCP iCal Server

What is the single MCP tool exposed by this server?

The server exposes one tool called send_to_calendar_agent. When invoked, it passes the user’s natural language request to a specialized calendar agent built with the OpenAI Agent SDK.

How does this server differ from traditional MCP implementations?

Traditional MCP servers expose multiple tools for different operations. This server uses an agent-based approach with a single entry point, stateful conversations, and automatic natural language processing, simplifying client integration.

What are the prerequisites for using MCP iCal Server?

You need macOS with the Calendar app configured, the uv package manager, an OpenAI API key set as the OPENAI_API_KEY environment variable, and an MCP-compatible client (Claude for Desktop is recommended).

Are there any known issues with recurring events?

Non-standard recurring schedules may not always be set correctly. Better results are achieved with more powerful LLM models. Reminder timing for recurring all-day events may be off by one day.

How do I grant calendar permissions to the server?

Claude (or your MCP client) must be launched from the terminal (e.g., /Applications/Claude.app/Contents/MacOS/Claude) to properly trigger the macOS calendar permissions prompt. Launching from Finder will not work.