AI agents call list_acl to retrieve information from Gcalendar without modifying anything — typically the context-gathering step in research, monitoring, and reporting workflows, before the agent takes action elsewhere.
This tool retrieves and enumerates access control rules for Google Calendar resources. It performs a query operation with no side effects—it does not create, modify, delete, or execute actions. While ACL information could theoretically inform privilege escalation attacks, the tool itself is read-only and represents minimal direct risk.
From the tool's definition Tool name 'list_acl' and description 'List access control rules' indicate retrieval of existing access control configuration without modification.
Attacks that exploit this kind of access
List access control rules. It is categorised as a Read tool in the Gcalendar MCP Server, which means it retrieves data without modifying state.
Register the Gcalendar MCP server in PolicyLayer and add a rule for list_acl: 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 Gcalendar. Nothing to install.
list_acl 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_acl 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_acl. 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_acl is provided by the Gcalendar MCP server (sandeepmallareddy/gcalendar-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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