send_contact_message · Whatsapp MCP: Risk & Policy

WHAT IT DOES

What send_contact_message does on Whatsapp

AI agents use send_contact_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_contact_message needs a policy

This tool creates outbound communication artifacts (contact card messages) via WhatsApp's API. It is a Write operation because it creates new data (messages) with side effects (delivery to recipients), but it is not Destructive (not deletion/overwrite), not Execute (no arbitrary code execution), and not Financial (no money movement).

From the tool's definition Tool name is 'send_contact_message' and description states 'Send one or more contact cards.' This performs a sending action that creates/modifies state in WhatsApp (outbound messages are recorded, conversations are updated).

Attacks that exploit this kind of access

Recommended rule Ready

Verdict

send_contact_message Rate-limited

send_contact_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_contact_message": {
      "limits": [
        {
          "counter": "send_contact_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_contact_message

What does the send_contact_message tool do? +

Send one or more contact cards. 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_contact_message? +

Register the Whatsapp MCP server in PolicyLayer and add a rule for send_contact_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_contact_message? +

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

Can I rate-limit send_contact_message? +

Yes. Add a rate_limit block to the send_contact_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_contact_message completely? +

Set action: deny in the PolicyLayer policy for send_contact_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_contact_message? +

send_contact_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.