AI agents call gmail_search_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/queries email messages without creating, modifying, or deleting data. It has no side effects beyond data retrieval. However, severity is elevated to 'high' because email messages often contain sensitive personal information (passwords, tokens, private communications, financial details, PII), and an AI agent with uncontrolled search access could exfiltrate large volumes of such data.
From the tool's definition Tool name 'gmail_search_messages' and description 'Search messages using Gmail search syntax' indicate retrieval of message data with no modification or deletion. The word 'Search' is a typical Read operation.
Documented attack patterns abuse exactly the kind of access gmail_search_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_search_messages:
{
"version": "1",
"default": "deny",
"tools": {
"gmail_search_messages": {}
}
}gmail_search_messages is read-only, so it stays allowed — but everything else on the server is denied unless you say otherwise.
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Search messages using Gmail search syntax (e.g.,. 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_search_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_search_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_search_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_search_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_search_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.