Google Calendar Automation

Google Calendar Automation via Rube MCP

Automate Google Calendar workflows including event creation, scheduling, availability checks, attendee management, and calendar browsing through Composio's Google Calendar toolkit.

Toolkit docs: composio.dev/toolkits/googlecalendar

Prerequisites

• Rube MCP must be connected (RUBE_SEARCH_TOOLS available)
• Active Google Calendar connection via RUBE_MANAGE_CONNECTIONS with toolkit googlecalendar
• Always call RUBE_SEARCH_TOOLS first to get current tool schemas

Setup

Get Rube MCP: Add https://rube.app/mcp as an MCP server in your client configuration. No API keys needed — just add the endpoint and it works.

1. Verify Rube MCP is available by confirming RUBE_SEARCH_TOOLS responds
2. Call RUBE_MANAGE_CONNECTIONS with toolkit googlecalendar
3. If connection is not ACTIVE, follow the returned auth link to complete Google OAuth
4. Confirm connection status shows ACTIVE before running any workflows

Core Workflows

1. Create and Manage Events

When to use: User wants to create, update, or delete calendar events

Tool sequence:

1. GOOGLECALENDAR_LIST_CALENDARS - Identify target calendar ID [Prerequisite]
2. GOOGLECALENDAR_GET_CURRENT_DATE_TIME - Get current time with proper timezone [Optional]
3. GOOGLECALENDAR_FIND_FREE_SLOTS - Check availability before booking [Optional]
4. GOOGLECALENDAR_CREATE_EVENT - Create the event [Required]
5. GOOGLECALENDAR_PATCH_EVENT - Update specific fields of an existing event [Alternative]
6. GOOGLECALENDAR_UPDATE_EVENT - Full replacement update of an event [Alternative]
7. GOOGLECALENDAR_DELETE_EVENT - Delete an event [Optional]

Key parameters:

• calendar_id: Use 'primary' for main calendar, or specific calendar ID
• start_datetime: ISO 8601 format 'YYYY-MM-DDTHH:MM:SS' (NOT natural language)
• timezone: IANA timezone name (e.g., 'America/New_York', NOT 'EST' or 'PST')
• event_duration_hour: Hours (0+)
• event_duration_minutes: Minutes (0-59 only; NEVER use 60+)
• summary: Event title
• attendees: Array of email addresses (NOT names)
• location: Free-form text for event location

Pitfalls:

• start_datetime must be ISO 8601; natural language like 'tomorrow' is rejected
• event_duration_minutes max is 59; use event_duration_hour=1 instead of event_duration_minutes=60
• timezone must be IANA identifier; abbreviations like 'EST', 'PST' are NOT valid
• attendees only accepts email addresses, not names; resolve names first
• Google Meet link creation defaults to true; may fail on personal Gmail accounts (graceful fallback)
• Organizer is auto-added as attendee unless exclude_organizer=true

2. List and Search Events

When to use: User wants to find or browse events on their calendar

Tool sequence:

1. GOOGLECALENDAR_LIST_CALENDARS - Get available calendars [Prerequisite]
2. GOOGLECALENDAR_FIND_EVENT - Search by title/keyword with time bounds [Required]
3. GOOGLECALENDAR_EVENTS_LIST - List events in a time range [Alternative]
4. GOOGLECALENDAR_EVENTS_INSTANCES - List instances of a recurring event [Optional]

Key parameters:

• query / q: Free-text search (matches summary, description, location, attendees)
• timeMin: Lower bound (RFC3339 with timezone offset, e.g., '2024-01-01T00:00:00-08:00')
• timeMax: Upper bound (RFC3339 with timezone offset)
• singleEvents: true to expand recurring events into instances
• orderBy: 'startTime' (requires singleEvents=true) or 'updated'
• maxResults: Results per page (max 2500)

Pitfalls:

• Timezone warning: UTC timestamps (ending in 'Z') don't align with local dates; use local timezone offsets instead
• Example: '2026-01-19T00:00:00Z' covers 2026-01-18 4pm to 2026-01-19 4pm in PST
• Omitting timeMin/timeMax scans the full calendar and can be slow
• pageToken in response means more results; paginate until absent
• orderBy='startTime' requires singleEvents=true

3. Manage Attendees and Invitations

When to use: User wants to add, remove, or update event attendees

Tool sequence:

1. GOOGLECALENDAR_FIND_EVENT or GOOGLECALENDAR_EVENTS_LIST - Find the event [Prerequisite]
2. GOOGLECALENDAR_PATCH_EVENT - Add attendees (replaces entire attendees list) [Required]
3. GOOGLECALENDAR_REMOVE_ATTENDEE - Remove a specific attendee by email [Required]

Key parameters:

• event_id: Unique event identifier (opaque string, NOT the event title)
• attendees: Full list of attendee emails (PATCH replaces entire list)
• attendee_email: Email to remove
• send_updates: 'all', 'externalOnly', or 'none'

Pitfalls:

• event_id is a technical identifier, NOT the event title; always search first to get the ID
• PATCH_EVENT attendees field replaces the entire list; include existing attendees to avoid removing them
• Attendee names cannot be resolved; always use email addresses
• Use GMAIL_SEARCH_PEOPLE to resolve names to emails before managing attendees

4. Check Availability and Free/Busy Status

When to use: User wants to find available time slots or check busy periods

Tool sequence:

1. GOOGLECALENDAR_LIST_CALENDARS - Identify calendars to check [Prerequisite]
2. GOOGLECALENDAR_GET_CURRENT_DATE_TIME - Get current time with timezone [Optional]
3. GOOGLECALENDAR_FIND_FREE_SLOTS - Find free intervals across calendars [Required]
4. GOOGLECALENDAR_FREE_BUSY_QUERY - Get raw busy periods for computing gaps [Fallback]
5. GOOGLECALENDAR_CREATE_EVENT - Book a confirmed slot [Required]

Key parameters:

• items: List of calendar IDs to check (e.g., ['primary'])
• time_min/time_max: Query interval (defaults to current day if omitted)
• timezone: IANA timezone for interpreting naive timestamps
• calendarExpansionMax: Max calendars (1-50)
• groupExpansionMax: Max members per group (1-100)

Pitfalls:

• Maximum span ~90 days per Google Calendar freeBusy API limit
• Very long ranges or inaccessible calendars yield empty/invalid results
• Only calendars with at least freeBusyReader access are visible
• Free slots responses may normalize to UTC ('Z'); check offsets
• GOOGLECALENDAR_FREE_BUSY_QUERY requires RFC3339 timestamps with timezone

Common Patterns

ID Resolution

• Calendar name -> calendar_id: GOOGLECALENDAR_LIST_CALENDARS to enumerate all calendars
• Event title -> event_id: GOOGLECALENDAR_FIND_EVENT or GOOGLECALENDAR_EVENTS_LIST
• Attendee name -> email: GMAIL_SEARCH_PEOPLE

Timezone Handling

• Always use IANA timezone identifiers (e.g., 'America/Los_Angeles')
• Use GOOGLECALENDAR_GET_CURRENT_DATE_TIME to get current time in user's timezone
• When querying events for a local date, use timestamps with local offset, NOT UTC
• Example: '2026-01-19T00:00:00-08:00' for PST, NOT '2026-01-19T00:00:00Z'

Pagination

• GOOGLECALENDAR_EVENTS_LIST returns nextPageToken; iterate until absent
• GOOGLECALENDAR_LIST_CALENDARS also paginates; use page_token

Known Pitfalls

• Natural language dates: NOT supported; all dates must be ISO 8601 or RFC3339
• Timezone mismatch: UTC timestamps don't align with local dates for filtering
• Duration limits: event_duration_minutes max 59; use hours for longer durations
• IANA timezones only: 'EST', 'PST', etc. are NOT valid; use 'America/New_York'
• Event IDs are opaque: Always search to get event_id; never guess or construct
• Attendees as emails: Names cannot be used; resolve with GMAIL_SEARCH_PEOPLE
• PATCH replaces attendees: Include all desired attendees in the array, not just new ones
• Conference limitations: Google Meet may fail on personal accounts (graceful fallback)
• Rate limits: High-volume searches can trigger 403/429; throttle between calls

Quick Reference

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Source: davepoon/buildwithclaude → plugins/all-skills/skills/google-calendar-automation/SKILL.md