calendar_list_calendars
AI agents call calendar_list_calendars to retrieve information from Google Calendar MCP Server without modifying anything — typically the context-gathering step in research, monitoring, and reporting workflows, before the agent takes action elsewhere.
This tool lists available calendars, a retrieval operation with no side effects. It enables querying calendar metadata but does not create, modify, or delete data. Low severity because disclosure of calendar names poses minimal risk; the sibling destructive and write operations (calendar_delete_event, calendar_create_event, calendar_update_event) are distinct tools requiring separate invocation.
From the tool's definition Tool name is 'calendar_list_calendars', which is a listing/enumeration operation on the sibling tool pattern (other tools include calendar_list_events, calendar_daily_agenda, calendar_search) that all retrieve calendar data.
Attacks that exploit this kind of access
calendar_list_calendars. It is categorised as a Read tool in the Google Calendar MCP Server MCP Server, which means it retrieves data without modifying state.
Register the Google Calendar MCP Server MCP server in PolicyLayer and add a rule for calendar_list_calendars: 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 Google Calendar MCP Server. Nothing to install.
calendar_list_calendars 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 calendar_list_calendars 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 calendar_list_calendars. 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.
calendar_list_calendars is provided by the Google Calendar MCP Server MCP server (murphy360/mcp_google_calendar). 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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