Make calendar_id optional in list_events tool

When no calendar_id is provided, lists events from all calendars.
Events include calendar_name field when listing from all calendars.

🤖 Generated with [Claude Code](https://claude.com/claude-code)

Co-Authored-By: Claude Opus 4.5 <noreply@anthropic.com>

src/tools/calendar_tools.py

@@ -13,24 +13,50 @@ def register_calendar_tools(mcp: FastMCP, service: CalendarService):
         calendars = service.list_calendars()
         return [c.model_dump() for c in calendars]
 
-    @mcp.tool(description="List events in a calendar within a specified date range. Supports recurring event expansion.")
+    @mcp.tool(description="List events within a date range. If no calendar is specified, lists events from all calendars.")
     def list_events(
-        calendar_id: str,
         start_date: str,
         end_date: str,
+        calendar_id: Optional[str] = None,
         include_recurring: bool = True,
     ) -> dict:
         """
         List events in a date range.
 
         Args:
-            calendar_id: The calendar ID (URL) to query
             start_date: Start of date range (ISO format: YYYY-MM-DD)
             end_date: End of date range (ISO format: YYYY-MM-DD)
+            calendar_id: The calendar ID (URL) to query. If not provided, lists from all calendars.
             include_recurring: Whether to expand recurring events (default: True)
         """
+        if calendar_id:
+            # Single calendar
             result = service.list_events(calendar_id, start_date, end_date, include_recurring)
             return result.model_dump()
+        else:
+            # All calendars
+            calendars = service.list_calendars()
+            all_events = []
+            for cal in calendars:
+                try:
+                    result = service.list_events(cal.id, start_date, end_date, include_recurring)
+                    for event in result.events:
+                        event_dict = event.model_dump()
+                        event_dict["calendar_name"] = cal.name
+                        all_events.append(event_dict)
+                except Exception:
+                    continue  # Skip calendars that fail
+
+            # Sort by start time
+            all_events.sort(key=lambda e: e.get("start", ""))
+
+            return {
+                "events": all_events,
+                "total": len(all_events),
+                "calendar_id": "all",
+                "start_date": start_date,
+                "end_date": end_date,
+            }
 
     @mcp.tool(description="Get detailed information about a specific calendar event including attendees and recurrence.")
     def get_event(