List upcoming calendar events.
AI agents call calendar_list to retrieve information from Mariana Google MCP without modifying anything — typically the context-gathering step in research, monitoring, and reporting workflows, before the agent takes action elsewhere.
This tool queries calendar data and returns a list of events. It does not create, modify, delete, execute code, or involve financial transactions. It is a straightforward read operation with minimal blast radius—calendar data leakage is a privacy concern but not actionable harm.
From the tool's definition Tool name 'calendar_list' and description 'List upcoming calendar events' both indicate a retrieval operation with no modification or side effects.
Attacks that exploit this kind of access
List upcoming calendar events. It is categorised as a Read tool in the Mariana Google MCP MCP Server, which means it retrieves data without modifying state.
Register the Mariana Google MCP server in PolicyLayer and add a rule for calendar_list: 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 Mariana Google MCP. Nothing to install.
calendar_list 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 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. 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 is provided by the Mariana Google MCP server (marianasmall/mariana-google-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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