AI agents call list_calendars_tool to retrieve information from Apps Script MCP without modifying anything — typically the context-gathering step in research, monitoring, and reporting workflows, before the agent takes action elsewhere.
This tool retrieves calendar metadata without creating, modifying, deleting, or executing any actions. It is a straightforward read operation with minimal security impact, as it only exposes information about calendars the user already has access to.
From the tool's definition Tool name and description indicate it 'List all calendars accessible to the user' — a query operation that retrieves calendar data with no modification or side effects.
Documented attack patterns abuse exactly the kind of access list_calendars_tool gives an agent:
PolicyLayer is an MCP gateway — it sits between your AI agents and Apps Script MCP, and nothing reaches the server without passing your rules. This is the rule we recommend for list_calendars_tool:
{
"version": "1",
"default": "deny",
"tools": {
"list_calendars_tool": {}
}
}list_calendars_tool is read-only, so it stays allowed — but everything else on the server is denied unless you say otherwise.
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List all calendars accessible to the user. It is categorised as a Read tool in the Apps Script MCP MCP Server, which means it retrieves data without modifying state.
Register the Apps Script MCP server in PolicyLayer and add a rule for list_calendars_tool: 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 Apps Script MCP. Nothing to install.
list_calendars_tool 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_tool 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_tool. 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_tool is provided by the Apps Script MCP server (sam-ent/google-automation-mcp). PolicyLayer sits as a proxy in front of this server to enforce policies before tool calls reach the server.
Start from Apps Script MCP, add the rest of your stack, and see everything your agents can call. Then put policy on all of it.
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60 Apps Script MCP tools catalogued and risk-classified — across an index of 43,000+ MCP servers.