Assign all emails sent with the labels.
AI agents use add_labels to create or update resources in Gmail — usually the action step of a workflow, after the agent has gathered context. Every call changes real data in your Gmail environment.
Adding labels to emails is a write operation that modifies email attributes reversibly without deleting or destroying data. The severity is medium rather than low because bulk label assignment could affect large numbers of emails and potentially cause organizational/classification issues, but the effect is reversible (labels can be removed).
From the tool's definition Tool description states 'Assign all emails sent with the labels' — this modifies email metadata by adding labels to existing emails. The verb 'assign' indicates a reversible modification operation.
Documented attack patterns abuse exactly the kind of access add_labels gives an agent:
PolicyLayer is an MCP gateway — it sits between your AI agents and Gmail, and nothing reaches the server without passing your rules. This is the rule we recommend for add_labels:
{
"version": "1",
"default": "deny",
"tools": {
"add_labels": {
"limits": [
{
"counter": "add_labels_rate",
"window": "minute",
"max": 30,
"scope": "grant"
}
]
}
}
}add_labels 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.
Free to start. No card required.
Assign all emails sent with the labels. It is categorised as a Write tool in the Gmail MCP Server, which means it can create or modify data. Consider rate limits to prevent runaway writes.
Register the Gmail MCP server in PolicyLayer and add a rule for add_labels: 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. Nothing to install.
add_labels 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 add_labels 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 add_labels. 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.
add_labels is provided by the Gmail MCP server (ivanlhz/gmail-mcp-server). PolicyLayer sits as a proxy in front of this server to enforce policies before tool calls reach the server.
Start from Gmail, 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.
12 Gmail tools catalogued and risk-classified — across an index of 43,000+ MCP servers.