send_email · MCP Playground MCP: Risk & Policy

WHAT IT DOES

What send_email does on MCP Playground

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

WHY IT NEEDS A POLICY

Why send_email needs a policy

The tool name and server description strongly imply this tool sends emails via Mailtrap, which is an outbound communication action. Sending emails is a Write/Execute-class operation with real-world side effects (external communication). However, since Mailtrap is a mail-testing service (not a live mail delivery service), blast radius may be somewhat limited. The description is empty, so confidence is reduced.

From the tool's definition Tool name is 'send_email'; server description mentions 'sending emails via Mailtrap'

Attacks that exploit this kind of access

Recommended rule Ready

Verdict

send_email Rate-limited

send_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": {
    "send_email": {
      "limits": [
        {
          "counter": "send_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 MCP Playground, so you can run agents against it safely.

FAQ

Questions about send_email

What does the send_email tool do? +

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

How do I enforce a policy on send_email? +

Register the MCP Playground MCP server in PolicyLayer and add a rule for send_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 MCP Playground. Nothing to install.

What risk level is send_email? +

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

Can I rate-limit send_email? +

Yes. Add a rate_limit block to the send_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 send_email completely? +

Set action: deny in the PolicyLayer policy for send_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 send_email? +

send_email is provided by the MCP Playground MCP server (jaanlavaerts/mcp_playground). PolicyLayer sits as a proxy in front of this server to enforce policies before tool calls reach the server.