AI agents use apply-label to create or update resources in Enhanced Gmail MCP Server — usually the action step of a workflow, after the agent has gathered context. Every call changes real data in your Enhanced Gmail MCP Server environment.
Applying a label is a reversible write operation that organizes emails by adding categorical metadata. It does not read sensitive data without user intent, does not execute arbitrary code, and does not delete or cause financial harm.
From the tool's definition Tool description states 'Applies a label to an email', which is a metadata modification operation that creates or modifies email labels/tags without altering message content or deleting data.
Documented attack patterns abuse exactly the kind of access apply-label gives an agent:
PolicyLayer is an MCP gateway — it sits between your AI agents and Enhanced Gmail MCP Server, and nothing reaches the server without passing your rules. This is the rule we recommend for apply-label:
{
"version": "1",
"default": "deny",
"tools": {
"apply-label": {
"limits": [
{
"counter": "apply-label_rate",
"window": "minute",
"max": 30,
"scope": "grant"
}
]
}
}
}apply-label stays usable, but capped — an agent stuck in a loop can't make hundreds of changes a minute. Everything else on the server is denied unless you say otherwise.
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Applies a label to an email. It is categorised as a Write tool in the Enhanced Gmail MCP Server MCP Server, which means it can create or modify data. Consider rate limits to prevent runaway writes.
Register the Enhanced Gmail MCP Server MCP server in PolicyLayer and add a rule for apply-label: 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 Enhanced Gmail MCP Server. Nothing to install.
apply-label is a Write tool with medium risk. Write tools should be rate-limited to prevent accidental bulk modifications.
Yes. Add a rate_limit block to the apply-label 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 apply-label. 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.
apply-label is provided by the Enhanced Gmail MCP Server MCP server (theposch/gmail-mcp). PolicyLayer sits as a proxy in front of this server to enforce policies before tool calls reach the server.
Start from Enhanced Gmail MCP Server, add the rest of your stack, and see everything your agents can call. Then put policy on all of it.
Free to start. No card required.
27 Enhanced Gmail MCP Server tools catalogued and risk-classified — across an index of 43,000+ MCP servers.