AI agents call list_delegates to retrieve information from Gmail MCP without modifying anything — typically the context-gathering step in research, monitoring, and reporting workflows, before the agent takes action elsewhere.
This tool only queries and returns existing delegate information without creating, modifying, or deleting data. Listing delegates is a read-only operation that poses minimal risk. The severity is low because delegate information, while sensitive, is typically restricted by Gmail's access controls and the tool itself performs no destructive or executory action.
From the tool's definition Tool name is 'list_delegates' and description states 'Lists the delegates for the specified account' — a pure retrieval operation with no modification or side effects.
Documented attack patterns abuse exactly the kind of access list_delegates gives an agent:
PolicyLayer is an MCP gateway — it sits between your AI agents and Gmail MCP, and nothing reaches the server without passing your rules. This is the rule we recommend for list_delegates:
{
"version": "1",
"default": "deny",
"tools": {
"list_delegates": {}
}
}list_delegates is read-only, so it stays allowed — but everything else on the server is denied unless you say otherwise.
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Lists the delegates for the specified account. It is categorised as a Read tool in the Gmail MCP MCP Server, which means it retrieves data without modifying state.
Register the Gmail MCP server in PolicyLayer and add a rule for list_delegates: 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 MCP. Nothing to install.
list_delegates 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_delegates 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_delegates. 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_delegates is provided by the Gmail MCP server (shinzo-labs/gmail-mcp). PolicyLayer sits as a proxy in front of this server to enforce policies before tool calls reach the server.
Deterministic rules across all 65 Gmail MCP tools. Per-identity grants. Full audit log. Live in minutes. Nothing to install.
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65 Gmail MCP tools catalogued and risk-classified — across an index of 42,500+ MCP servers.