AI agents call gmail_list_messages to retrieve information from Sage MCP without modifying anything — typically the context-gathering step in research, monitoring, and reporting workflows, before the agent takes action elsewhere.
This tool retrieves or lists email messages without creating, modifying, or deleting them. It is a read-only operation. Severity is medium rather than low because email messages often contain sensitive personal, financial, or business information; unauthorized listing could expose significant private data, though the blast radius is limited to the messages themselves without further actions.
From the tool's definition Tool name 'gmail_list_messages' and description 'List messages in the user' indicate a query/retrieval operation with no modification or deletion of data.
Documented attack patterns abuse exactly the kind of access gmail_list_messages gives an agent:
PolicyLayer is an MCP gateway — it sits between your AI agents and Sage MCP, and nothing reaches the server without passing your rules. This is the rule we recommend for gmail_list_messages:
{
"version": "1",
"default": "deny",
"tools": {
"gmail_list_messages": {}
}
}gmail_list_messages is read-only, so it stays allowed — but everything else on the server is denied unless you say otherwise.
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List messages in the user. It is categorised as a Read tool in the Sage MCP MCP Server, which means it retrieves data without modifying state.
Register the Sage MCP server in PolicyLayer and add a rule for gmail_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 Sage MCP. Nothing to install.
gmail_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 gmail_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 gmail_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.
gmail_list_messages is provided by the Sage MCP server (sagemcp/sagemcp). PolicyLayer sits as a proxy in front of this server to enforce policies before tool calls reach the server.
Deterministic rules across all 359 Sage MCP tools. Per-identity grants. Full audit log. Live in minutes. Nothing to install.
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359 Sage MCP tools catalogued and risk-classified — across an index of 42,500+ MCP servers.