AI agents call listCalendars to retrieve information from Outlook without modifying anything — typically the context-gathering step in research, monitoring, and reporting workflows, before the agent takes action elsewhere.
The tool retrieves calendar metadata without side effects. It enables discovery of available calendars but does not create, modify, delete, or execute any operations. The blast radius of misuse is minimal—an AI agent listing calendars cannot cause harm beyond information disclosure of calendar names the account holder already possesses.
From the tool's definition Tool name and description indicate listing calendars: 'List all calendars in Outlook.' This is a read-only query operation with no modification or deletion capability.
Attacks that exploit this kind of access
List all calendars in Outlook. It is categorised as a Read tool in the Outlook MCP Server, which means it retrieves data without modifying state.
Register the Outlook MCP server in PolicyLayer and add a rule for listCalendars: 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 Outlook. Nothing to install.
listCalendars 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 listCalendars 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 listCalendars. 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.
listCalendars is provided by the Outlook MCP server (lihaokun/outlook-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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