AI agents use gmail_modify_labels to create or update resources in Sage MCP — usually the action step of a workflow, after the agent has gathered context. Every call changes real data in your Sage MCP environment.
This tool modifies email labels (tags/folders) which changes how messages are organized and categorized in Gmail. While reversible (labels can be added back), this is a Write operation that alters message state. The severity is high because an adversary could manipulate labels to hide emails, reorganize inboxes, mark important messages as spam, or create confusion in email organization.
From the tool's definition Tool name 'gmail_modify_labels' and description 'Add or remove labels from a specific message' indicate modification of email metadata. The actions 'Add or remove labels' are reversible write operations on Gmail message attributes.
Documented attack patterns abuse exactly the kind of access gmail_modify_labels 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_modify_labels:
{
"version": "1",
"default": "deny",
"tools": {
"gmail_modify_labels": {
"limits": [
{
"counter": "gmail_modify_labels_rate",
"window": "minute",
"max": 30,
"scope": "grant"
}
]
}
}
}gmail_modify_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.
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Add or remove labels from a specific message. It is categorised as a Write tool in the Sage MCP MCP Server, which means it can create or modify data. Consider rate limits to prevent runaway writes.
Register the Sage MCP server in PolicyLayer and add a rule for gmail_modify_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 Sage MCP. Nothing to install.
gmail_modify_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 gmail_modify_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 gmail_modify_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.
gmail_modify_labels 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.