send_whatsapp_message · WhatsApp MCP: Risk & Policy

WHAT IT DOES

What send_whatsapp_message does on WhatsApp MCP

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

WHY IT NEEDS A POLICY

Why send_whatsapp_message needs a policy

This tool creates new data (messages) that can be deleted or edited later, making it a Write action rather than Read (it modifies state) or Destructive (deletion is reversible). Severity is medium because misuse could enable spam, harassment, or social engineering, but the blast radius is limited to message creation without access to financial systems or irreversible data destruction.

From the tool's definition Tool name 'send_whatsapp_message' and description 'Sends a WhatsApp text message to a phone number or group' indicate it creates and transmits messages, which are reversible writes.

Attacks that exploit this kind of access

Recommended rule Ready

Verdict

send_whatsapp_message Rate-limited

send_whatsapp_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_whatsapp_message": {
      "limits": [
        {
          "counter": "send_whatsapp_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 MCP, so you can run agents against it safely.

FAQ

Questions about send_whatsapp_message

What does the send_whatsapp_message tool do? +

Sends a WhatsApp text message to a phone number or group. The. It is categorised as a Write tool in the WhatsApp MCP 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_whatsapp_message? +

Register the WhatsApp MCP server in PolicyLayer and add a rule for send_whatsapp_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 MCP. Nothing to install.

What risk level is send_whatsapp_message? +

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

Can I rate-limit send_whatsapp_message? +

Yes. Add a rate_limit block to the send_whatsapp_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_whatsapp_message completely? +

Set action: deny in the PolicyLayer policy for send_whatsapp_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_whatsapp_message? +

send_whatsapp_message is provided by the WhatsApp MCP server (ponmanian-sa/whatsapp_mcp). PolicyLayer sits as a proxy in front of this server to enforce policies before tool calls reach the server.