Fastmail Calendar MCP Server

An MCP (Model Context Protocol) server that enables AI assistants to interact with Fastmail Calendar via CalDAV. This allows AI to view, create, modify, and delete calendar events in your Fastmail account.

Features

• List Calendars: View all calendars in your Fastmail account

• List Events: Retrieve events from a specific calendar within a date range

• Create Events: Add new calendar events with details like title, description, location, and time

• Update Events: Modify existing calendar events

• Delete Events: Remove calendar events

Configuration

This MCP server requires the following configuration:

• username: Your Fastmail email address (e.g., user@fastmail.com)

• appPassword: A Fastmail app password (16 characters)

Creating a Fastmail App Password

1. Log in to Fastmail

2. Go to Settings → Privacy & Security → Integrations

3. Click New app password

4. Select permissions (ensure "Calendars" is included)

5. Click Generate password

6. Copy the generated password (16 characters)

Installation

Via Smithery

Manual Installation for Claude Desktop

Add to your Claude Desktop config file (~/.config/claude/claude_desktop_config.json):

For Cursor IDE

Add to ~/.cursor/mcp.json:

Development

Setup

Running Locally

Development Mode

This will watch for changes and automatically rebuild.

Deploying to Smithery

1. Push this repository to GitHub

2. Go to smithery.ai

3. Click Deploy

4. Select your GitHub repository

5. Smithery will automatically detect the TypeScript MCP project and deploy it

Available Tools

list_calendars

Lists all calendars in your Fastmail account.

Returns: Array of calendar objects with displayName, url, description, and timezone.

list_events

Lists events from a specific calendar within a date range.

Parameters:

• calendarUrl (required): The URL of the calendar

• startDate (required): Start date in ISO format (e.g., "2024-01-01")

• endDate (required): End date in ISO format (e.g., "2024-12-31")

Returns: Array of event objects with url, etag, and data (iCalendar format).

create_event

Creates a new calendar event.

Parameters:

• calendarUrl (required): The calendar URL where the event will be created

• summary (required): Event title

• startDate (required): Event start date/time in ISO format

• endDate (required): Event end date/time in ISO format

• description (optional): Event description

• location (optional): Event location

Returns: Success message with the created event URL.

update_event

Updates an existing calendar event.

Parameters:

• eventUrl (required): The URL of the event to update

• summary (optional): New event title

• description (optional): New event description

• startDate (optional): New start date/time in ISO format

• endDate (optional): New end date/time in ISO format

• location (optional): New event location

Returns: Success message.

delete_event

Deletes a calendar event.

Parameters:

• eventUrl (required): The URL of the event to delete

• etag (required): The etag of the event (obtained from list_events)

Returns: Success message.

Example Usage

Once installed, you can ask your AI assistant:

• "List my Fastmail calendars"

• "Show me my calendar events for next week"

• "Create a meeting on December 15th at 2 PM titled 'Team Sync'"

• "Update the 'Team Sync' event to include a Zoom link in the description"

• "Delete the event with URL [event-url]"

Security Notes

• Never commit your Fastmail app password to version control

• Use environment variables or secure secret management

• App passwords are safer than your main Fastmail password

• You can revoke app passwords at any time from Fastmail settings

License

MIT