AI agents call list-calendars to retrieve information from macOS 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 queries and returns a list of available calendars on macOS. It performs no modifications, deletions, or external operations—purely informational retrieval. It belongs in the Read category with low severity since calendar enumeration has minimal blast radius even if misused by an AI agent.
From the tool's definition Tool name 'list-calendars' and description '列出所有macOS日历' (list all macOS calendars) indicate retrieval of calendar data with no side effects.
Documented attack patterns abuse exactly the kind of access list-calendars gives an agent:
PolicyLayer is an MCP gateway — it sits between your AI agents and macOS Calendar MCP Server, and nothing reaches the server without passing your rules. This is the rule we recommend for list-calendars:
{
"version": "1",
"default": "deny",
"tools": {
"list-calendars": {}
}
}list-calendars is read-only, so it stays allowed — but everything else on the server is denied unless you say otherwise.
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列出所有macOS日历. It is categorised as a Read tool in the macOS Calendar MCP Server MCP Server, which means it retrieves data without modifying state.
Register the macOS Calendar MCP Server MCP server in PolicyLayer and add a rule for 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 macOS Calendar MCP Server. Nothing to install.
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 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 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.
list-calendars is provided by the macOS Calendar MCP Server MCP server (xybstone/macos-calendar-mcp). PolicyLayer sits as a proxy in front of this server to enforce policies before tool calls reach the server.
Start from macOS Calendar MCP Server, add the rest of your stack, and see everything your agents can call. Then put policy on all of it.
Free to start. No card required.
8 macOS Calendar MCP Server tools catalogued and risk-classified — across an index of 43,000+ MCP servers.