forward_email · Nexus Core MCP: Risk & Policy

WHAT IT DOES

What forward_email does on Nexus Core

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

WHY IT NEEDS A POLICY

Why forward_email needs a policy

This tool creates a new email draft by forwarding an existing message. It modifies state by creating a draft object, but does not trigger any destructive or irreversible action. The explicit clarification that it 'does NOT auto-send' confirms the action is reversible—the draft can be discarded or edited before sending.

From the tool's definition Tool description states: 'Create a forwarded draft (does NOT auto-send)'. The verb 'Create' and explicit mention that it produces a draft (not yet sent) indicates data creation/modification without irreversible effects.

Attacks that exploit this kind of access

Recommended rule Ready

Verdict

forward_email Rate-limited

forward_email 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": {
    "forward_email": {
      "limits": [
        {
          "counter": "forward_email_rate",
          "window": "minute",
          "max": 30,
          "scope": "grant"
        }
      ]
    }
  }
}

LIMIT THIS TOOL →

Instant setup, no code required.

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

FAQ

Questions about forward_email

What does the forward_email tool do? +

Create a forwarded draft (does NOT auto-send). Use send_email to dispatch. It is categorised as a Write tool in the Nexus Core MCP Server, which means it can create or modify data. Consider rate limits to prevent runaway writes.

How do I enforce a policy on forward_email? +

Register the Nexus Core MCP server in PolicyLayer and add a rule for forward_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 Nexus Core. Nothing to install.

What risk level is forward_email? +

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

Can I rate-limit forward_email? +

Yes. Add a rate_limit block to the forward_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 forward_email completely? +

Set action: deny in the PolicyLayer policy for forward_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 forward_email? +

forward_email is provided by the Nexus Core MCP server (noumenon-ai/nexus-core). PolicyLayer sits as a proxy in front of this server to enforce policies before tool calls reach the server.