AI agents call list_smime_info 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 retrieves S/MIME (Secure/Multipurpose Internet Mail Extensions) configuration information for a send-as alias. It performs a read-only query operation with no capability to modify, delete, or execute actions. The blast radius is minimal—unauthorized access would expose email security settings but not enable message manipulation, deletion, or financial transactions.
From the tool's definition Tool name 'list_smime_info' uses 'list', a retrieval verb. Description states 'Lists S/MIME configs', indicating it queries and returns configuration data without modification or side effects.
Documented attack patterns abuse exactly the kind of access list_smime_info 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_smime_info:
{
"version": "1",
"default": "deny",
"tools": {
"list_smime_info": {}
}
}list_smime_info is read-only, so it stays allowed — but everything else on the server is denied unless you say otherwise.
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Lists S/MIME configs for the specified send-as alias. 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_smime_info: 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_smime_info 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_smime_info 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_smime_info. 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_smime_info 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.
Free to start. No card required.
65 Gmail MCP tools catalogued and risk-classified — across an index of 42,500+ MCP servers.