List messages in an email folder
AI agents call list_messages to retrieve information from Mail Cal Drive without modifying anything — typically the context-gathering step in research, monitoring, and reporting workflows, before the agent takes action elsewhere.
This tool retrieves or queries email messages from a folder without creating, modifying, or deleting any data. It is a pure read operation with no side effects. The severity is low because listing messages poses minimal risk even if an AI agent performs the action unintentionally, as it only exposes information the authenticated user already has access to.
From the tool's definition Tool name 'list_messages' and description 'List messages in an email folder' clearly indicate a retrieval operation with no modification or deletion of data.
Attacks that exploit this kind of access
List messages in an email folder. It is categorised as a Read tool in the Mail Cal Drive MCP Server, which means it retrieves data without modifying state.
Register the Mail Cal Drive MCP server in PolicyLayer and add a rule for list_messages: 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 Mail Cal Drive. Nothing to install.
list_messages 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_messages 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_messages. 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_messages is provided by the Mail Cal Drive MCP server (rumbitopi/mail-cal-drive-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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