markdown-to-gcal

name	markdown-to-gcal
description	Create and update Google Calendar events from structured markdown files using MCP. Supports idempotent sync - running multiple times on the same markdown produces the same result.
license	Proprietary
metadata	{"author":"hadenlabs","version":"0.0.0","opencode":{"emoji":"📅","tags":["google-calendar","mcp","event","workflow"],"mcp":{"preferredServer":"google-calendar"}}}

Markdown to Google Calendar

Use this skill when you have a markdown file with event details and want to create a Google Calendar event using MCP.

Objective

Convert a structured markdown file into a Google Calendar event using the @cocal/google-calendar-mcp MCP.

Invocation Patterns

This skill can be triggered when the user intent matches:

• creating calendar events from markdown
• syncing markdown events with Google Calendar
• updating existing calendar events based on markdown

Example User Requests

• "Use the markdown-to-gcal skill with this file"
• "Create a Google Calendar event from this markdown"
• "Sync this markdown with my calendar"
• "Update this event in my calendar"

Expected Markdown Format

The markdown file should follow the event.md.tpl structure:

# Event: <title>

## Metadata

- start: <datetime>
- end: <datetime>
- timezone: <timezone>
- duration: <duration_optional>
- id: <event_id_optional>
- attendees:
  - <email1>
  - <email2>
- recurrence: <RRULE string>

## Description

<event description>

## Location

<location>

Date Format Options

Format	Example	Description
Simplified	2026-04-20 09:00	Recommended - no T, no timezone suffix
ISO 8601	2026-04-20T09:00:00-03:00	Full format
Natural	next monday 9am	Human readable
Relative	+1d	Days from now
Duration	1h30m	Use instead of end time

Required Metadata

• title - Event title (from # Event: heading)
• start - Start datetime (simplified: 2026-04-20 09:00, ISO 8601: 2026-04-20T09:00:00-03:00, or natural: next monday 9am)
• timezone - Timezone identifier (e.g., America/Argentina/Buenos_Aires)

Optional Metadata

• id - Google Calendar event ID (if present, validate and update; if absent, create new)
• end - End datetime (or use duration instead)
• duration - Event duration (e.g., 1h, 30m, 1h30m) as alternative to end
• attendees - List of email addresses
• recurrence - RRULE string for recurring events (e.g., FREQ=WEEKLY;BYDAY=MO)
• description - Event description
• location - Physical or virtual location

Operational Flow

1. Read the markdown file indicated by the user.
2. Parse the content to extract:
   • title from # Event: heading
   • id from Metadata section (optional - determines create vs update)
   • start, end, duration, timezone from Metadata section
   • attendees list from Metadata section
   • recurrence from Metadata section
   • description from Description section
   • location from Location section
3. Convert date formats to ISO 8601:
   • Simplified (2026-04-18 22:00): append :00 and timezone offset
   • ISO 8601 (2026-04-18T22:00:00-05:00): use as-is
   • Duration (1h): calculate end time by adding duration to start
4. Validate required fields are present.
5. Idempotent Create/Update Logic: a. If id is empty or not present → Create new event b. If id has a value:
   • First, validate existence using google-calendar_get-event
   • If event exists → Update the event
   • If event does NOT exist → Create new event (the old ID was invalid)
6. After create: If a new event was created (either from empty ID or invalid ID), add the returned id to the markdown file so future runs update instead of create
7. Return the result to the user.

MCP Tools Available

google-calendar_get-event

Get an event by ID to validate existence.

{
  "calendarId": "primary",
  "eventId": "<event-id>"
}

google-calendar_create-event

Create a new event.

{
  "calendarId": "primary",
  "summary": "<title>",
  "start": "<ISO 8601 datetime>",
  "end": "<ISO 8601 datetime>",
  "timeZone": "<timezone>",
  "description": "<description>",
  "location": "<location>",
  "attendees": [
    { "email": "<email1>" },
    { "email": "<email2>" }
  ],
  "recurrence": ["RRULE:<rrule>"]
}

google-calendar_update-event

Update an existing event.

{
  "calendarId": "primary",
  "eventId": "<event-id>",
  "summary": "<title>",
  "start": "<ISO 8601 datetime>",
  "end": "<ISO 8601 datetime>",
  "timeZone": "<timezone>",
  "description": "<description>",
  "location": "<location>"
}

Idempotent Flow (Recommended)

Step 1: Check if ID exists in markdown

• If NO id field → Skip to Step 3 (create new)
• If id field exists → Go to Step 2

Step 2: Validate event existence

Call google-calendar_get-event with the id from markdown:

• If returns event → Event exists → Go to Step 4 (update)
• If returns 404/not found → Event doesn't exist → Go to Step 3 (create new)
• If returns other error → STOP and report error

Step 3: Create new event

Call google-calendar_create-event:

• The response contains event.id
• Write this id back to the markdown file in the Metadata section
• Future runs will use this ID for updates

Step 4: Update existing event

Call google-calendar_update-event with the existing id:

• No need to update the markdown (ID stays the same)

Idempotent Behavior Examples

Example 1: First Execution (No ID)

Before:

# Event: Team Standup

## Metadata

- start: 2026-04-22 09:00
- duration: 30m
- timezone: America/Argentina/Buenos_Aires

After:

# Event: Team Standup

## Metadata

- start: 2026-04-22 09:00
- duration: 30m
- timezone: America/Argentina/Buenos_Aires
- id: abc123def456ghi789

Example 2: Second Execution (With Valid ID)

The skill validates the ID exists in Google Calendar, then updates the event. No duplicate created.

Example 3: Invalid ID (Event Deleted)

Before:

- id: deleted-event-id

After:

- id: new-event-id-xyz

The old ID is replaced with the new event ID.

Validation Rules

• Required fields: title, start, timezone
• datetime can be: simplified (2026-04-20 09:00), ISO 8601 (2026-04-20T09:00:00-03:00), natural (next monday 9am), or relative (+1d)
• Use either end OR duration, not both
• attendees must be valid email addresses
• end time must be after start time (or duration must be positive)
• timezone must be a valid IANA timezone identifier

Error Handling

• If markdown is invalid or missing required fields, explain what is missing.
• If MCP tool fails, report the error from the MCP.
• Do not invent any field values.
• ID Validation Errors:
  • If google-calendar_get-event fails with "not found" (404) → treat as new event (create)
  • If google-calendar_get-event fails with any other error (auth, network, quota) → STOP and report error, do not attempt create
• Idempotency: The skill should produce the same result regardless of how many times it runs