AI agents call list_emails to retrieve information from Gmail without modifying anything — typically the context-gathering step in research, monitoring, and reporting workflows, before the agent takes action elsewhere.
This tool retrieves email metadata from a user's Gmail inbox. While categorized as Read (no side effects), the severity is high because emails often contain sensitive personal, financial, or confidential information. An AI agent with unrestricted access could exfiltrate large volumes of private communications. However, it does not modify, delete, or execute any actions—only queries and returns data.
From the tool's definition Tool name 'list_emails' and description 'List Gmail inbox messages' clearly indicate data retrieval with no modification. The ability to apply 'Gmail query filters' extends capability but remains read-only.
Attacks that exploit this kind of access
List Gmail inbox messages. Supports maxResults and Gmail query filters. It is categorised as a Read tool in the Gmail MCP Server, which means it retrieves data without modifying state.
Register the Gmail MCP server in PolicyLayer and add a rule for list_emails: 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 Gmail. Nothing to install.
list_emails 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_emails 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_emails. 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_emails is provided by the Gmail MCP server (symbolstar/gmail-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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