List individual instances of a recurring event
AI agents call list_event_instances to retrieve information from Calendar Mcp without modifying anything — typically the context-gathering step in research, monitoring, and reporting workflows, before the agent takes action elsewhere.
This tool queries and retrieves information about recurring event instances without creating, modifying, or deleting any data. It is a read-only operation that has no side effects on the calendar state.
From the tool's definition Tool name 'list_event_instances' and description 'List individual instances of a recurring event' indicate a retrieval operation with no modification or deletion of data.
Attacks that exploit this kind of access
List individual instances of a recurring event. It is categorised as a Read tool in the Calendar Mcp MCP Server, which means it retrieves data without modifying state.
Register the Calendar MCP server in PolicyLayer and add a rule for list_event_instances: 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 Calendar Mcp. Nothing to install.
list_event_instances is a Read tool with low risk. Read-only tools are generally safe to allow by default.
Yes. Add a rate_limit block to the list_event_instances 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 list_event_instances. 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.
list_event_instances is provided by the Calendar MCP server (ydrogen/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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