open-email · Gmail MCP Server MCP: Risk & Policy

WHAT IT DOES

What open-email does on Gmail MCP Server

AI agents invoke open-email to trigger actions in Gmail MCP Server. What it does depends on the arguments the agent supplies, and its effects often reach beyond the immediate call — builds kicked off, notifications sent, workflows started.

WHY IT NEEDS A POLICY

Why open-email needs a policy

Opening an email in a browser is an external operation that launches a browser and navigates to a resource. This is not a pure read (no data is returned to the agent) but rather an Execute action that triggers an external application. Misuse could expose email content in unintended contexts or trigger browser-based vulnerabilities, warranting medium severity.

From the tool's definition 'Open email in browser' — triggers an external browser action to open/display content

Attacks that exploit this kind of access

Recommended rule Ready

Verdict

open-email Rate-limited

open-email stays usable, but rate-capped — a runaway agent can't fire it dozens of times a minute. Everything else on the server is denied unless you say otherwise.

View as policy code

policy.json

{
  "version": "1",
  "default": "deny",
  "tools": {
    "open-email": {
      "limits": [
        {
          "counter": "open-email_rate",
          "window": "minute",
          "max": 10,
          "scope": "grant"
        }
      ]
    }
  }
}

RATE-LIMIT THIS TOOL →

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 open-email

What does the open-email tool do? +

Open email in browser. It is categorised as a Execute tool in the Gmail MCP Server MCP Server, which means it can trigger actions or run processes. Use rate limits and argument validation.

How do I enforce a policy on open-email? +

Register the Gmail MCP Server MCP server in PolicyLayer and add a rule for open-email: 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 open-email? +

open-email is a Execute tool with high risk. Execute tools should be rate-limited and have argument validation enabled.

Can I rate-limit open-email? +

Yes. Add a rate_limit block to the open-email 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 open-email completely? +

Set action: deny in the PolicyLayer policy for open-email. 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 open-email? +

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