PERMANENTLY DELETE an event. PREREQUISITE: You must first call list_calendars, then list_events to get both the eventUrl AND etag. WARNING: This cannot be undone. Always confirm with the user before deleting.
AI agents call delete_event to permanently remove resources in Fastmail Calendar MCP Server — typically in cleanup and lifecycle workflows. It does its job in a single call, and there is no undo.
delete_event performs irreversible deletion of calendar data. Even though it requires prerequisite steps (listing calendars/events) and includes a user confirmation warning, the action itself cannot be undone and constitutes permanent data loss. This is the canonical Destructive category.
From the tool's definition Tool description explicitly states 'PERMANENTLY DELETE' and 'This cannot be undone'. The tool irreversibly removes calendar events from the user's Fastmail calendar.
Attacks that exploit this kind of access
PERMANENTLY DELETE an event. PREREQUISITE: You must first call list_calendars, then list_events to get both the eventUrl AND etag. WARNING: This cannot be undone. Always confirm with the user before deleting. It is categorised as a Destructive tool in the Fastmail Calendar MCP Server MCP Server, which means it can permanently delete or destroy data. Block by default and require explicit approval.
Register the Fastmail Calendar MCP Server MCP server in PolicyLayer and add a rule for delete_event: allow, deny, rate-limit, or require approval. Point your MCP client at the PolicyLayer proxy URL and the rule is enforced on every call, before it reaches Fastmail Calendar MCP Server. Nothing to install.
delete_event is a Destructive tool with critical risk. Critical-risk tools should be blocked by default and only enabled with explicit human approval.
Yes. Add a rate_limit block to the delete_event rule in your PolicyLayer policy. For example, setting max: 10 and window: 60 limits the tool to 10 calls per minute. Rate limits are tracked per agent session and reset automatically.
Set action: deny in the PolicyLayer policy for delete_event. The AI agent will receive a policy violation error and cannot call the tool. You can also include a reason field to explain why the tool is blocked.
delete_event is provided by the Fastmail Calendar MCP Server MCP server (nova-3951/fastmail-calendar-mcp). PolicyLayer sits as a proxy in front of this server to enforce policies before tool calls reach the server.
Every MCP server has a record like this.
Type a name, get the same breakdown: verified identity, auth posture, risk grade, capabilities, recommended policy.
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