mark_gmail_unread · Gmail MCP Server MCP: Risk & Policy

WHAT IT DOES

What mark_gmail_unread does on Gmail MCP Server

AI agents use mark_gmail_unread to create or update resources in Gmail MCP Server — usually the action step of a workflow, after the agent has gathered context. Every call changes real data in your Gmail MCP Server environment.

WHY IT NEEDS A POLICY

Why mark_gmail_unread needs a policy

Marking messages as unread changes metadata state within Gmail but is fully reversible by marking them read again. This fits the Write category (creates or modifies data reversibly). The severity is medium because while the change is reversible, an agent could mark large volumes of messages as unread, cluttering a user's inbox and potentially causing operational disruption.

From the tool's definition Tool description: 'Mark Gmail messages as unread.' The action modifies message state (read status) in Gmail, which is a reversible write operation.

Attacks that exploit this kind of access

Recommended rule Ready

Verdict

mark_gmail_unread Rate-limited

mark_gmail_unread 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.

View as policy code

policy.json

{
  "version": "1",
  "default": "deny",
  "tools": {
    "mark_gmail_unread": {
      "limits": [
        {
          "counter": "mark_gmail_unread_rate",
          "window": "minute",
          "max": 30,
          "scope": "grant"
        }
      ]
    }
  }
}

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Instant setup, no code required.

PolicyLayer is an MCP gateway: every tool call is checked against your rule before it reaches Gmail MCP Server, so you can run agents against it safely.

FAQ

Questions about mark_gmail_unread

What does the mark_gmail_unread tool do? +

Mark Gmail messages as unread. It is categorised as a Write tool in the Gmail MCP Server MCP Server, which means it can create or modify data. Consider rate limits to prevent runaway writes.

How do I enforce a policy on mark_gmail_unread? +

Register the Gmail MCP Server MCP server in PolicyLayer and add a rule for mark_gmail_unread: 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 Server. Nothing to install.

What risk level is mark_gmail_unread? +

mark_gmail_unread is a Write tool with medium risk. Write tools should be rate-limited to prevent accidental bulk modifications.

Can I rate-limit mark_gmail_unread? +

Yes. Add a rate_limit block to the mark_gmail_unread 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.

How do I block mark_gmail_unread completely? +

Set action: deny in the PolicyLayer policy for mark_gmail_unread. 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.

What MCP server provides mark_gmail_unread? +

mark_gmail_unread is provided by the Gmail MCP Server MCP server (stevesimpson418/gmail-mcp-server). PolicyLayer sits as a proxy in front of this server to enforce policies before tool calls reach the server.