Google Calendar stays the system of record. Heldrey writes only the fields it owns, or creates blocks it manages. Nothing changes until you turn a rule on.
Using Heldrey
The objects you see in the app: rules, preview, Activity, Needs attention, and plan limits.
MCP
Use Heldrey from Claude, ChatGPT, or another client that supports remote MCP. Assistants interpret what you want. Heldrey validates and executes. An assistant never switches a custom rule on — you do that on a Heldrey page.