send_template_message · Whatsapp MCP: Risk & Policy

WHAT IT DOES

What send_template_message does on Whatsapp

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

WHY IT NEEDS A POLICY

Why send_template_message needs a policy

This tool creates/sends data (messages) to external recipients via WhatsApp, making it a Write operation. Severity is high because uncontrolled message sending could enable spam campaigns, harassment, or social engineering attacks impersonating the business. The tool is reversible only to the extent that sent messages can be deleted, but the communication itself has already occurred.

From the tool's definition Tool description states it "Send[s] an approved template message" which creates a new outbound message to WhatsApp users. The capability to "initiat[e] conversations outside the 24h window" demonstrates it has side effects on external communication channels.

Attacks that exploit this kind of access

Recommended rule Ready

Verdict

send_template_message Rate-limited

send_template_message 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_template_message": {
      "limits": [
        {
          "counter": "send_template_message_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 Whatsapp, so you can run agents against it safely.

FAQ

Questions about send_template_message

What does the send_template_message tool do? +

Send an approved template message. Required for initiating conversations outside the 24h window. Supports text parameters, media headers, and buttons. It is categorised as a Write tool in the Whatsapp 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_template_message? +

Register the Whatsapp MCP server in PolicyLayer and add a rule for send_template_message: 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 Whatsapp. Nothing to install.

What risk level is send_template_message? +

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

Can I rate-limit send_template_message? +

Yes. Add a rate_limit block to the send_template_message 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_template_message completely? +

Set action: deny in the PolicyLayer policy for send_template_message. 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_template_message? +

send_template_message is provided by the Whatsapp MCP server (spirit122/whatsapp-mcp-server). PolicyLayer sits as a proxy in front of this server to enforce policies before tool calls reach the server.