AI agents call list_threads 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 and queries email thread data from Gmail. It has no side effects—it does not create, modify, delete, or execute any operations. It falls squarely within the Read category as a data retrieval operation. Severity is low because listing threads exposes only metadata and thread information already accessible to the authenticated user, with minimal blast radius if misused by an AI agent.
From the tool's definition Tool name 'list_threads' and description 'List threads in the user' indicate retrieval of thread metadata without modification, deletion, or execution of external operations.
Documented attack patterns abuse exactly the kind of access list_threads 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_threads:
{
"version": "1",
"default": "deny",
"tools": {
"list_threads": {}
}
}list_threads is read-only, so it stays allowed — but everything else on the server is denied unless you say otherwise.
Free to start. No card required.
List threads in the user. 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_threads: 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_threads 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_threads 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_threads. 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_threads 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.