whatsapp_react · Waha MCP: Risk & Policy

WHAT IT DOES

What whatsapp_react does on Waha

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

WHY IT NEEDS A POLICY

Why whatsapp_react needs a policy

This tool sends or removes an emoji reaction on a WhatsApp message. It modifies state (adds/removes a reaction) but is reversible — reactions can be changed or removed. No data is permanently deleted, no code is executed, and no financial transaction occurs. Severity is medium because it acts on external communications on behalf of the user.

From the tool's definition React to a WhatsApp message with an emoji. Use an empty string for the reaction to remove an existing reaction.

Attacks that exploit this kind of access

Recommended rule Ready

Verdict

whatsapp_react Rate-limited

whatsapp_react 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": {
    "whatsapp_react": {
      "limits": [
        {
          "counter": "whatsapp_react_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 Waha, so you can run agents against it safely.

FAQ

Questions about whatsapp_react

What does the whatsapp_react tool do? +

React to a WhatsApp message with an emoji. Use an empty string for the reaction to remove an existing reaction. Args: - contactId: ${CONTACT_ID_DESC} - messageId: Message ID to react to (get from whatsapp_read_messages) - reaction: Emoji to react with (e.g.,. It is categorised as a Write tool in the Waha MCP Server, which means it can create or modify data. Consider rate limits to prevent runaway writes.

How do I enforce a policy on whatsapp_react? +

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

What risk level is whatsapp_react? +

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

Can I rate-limit whatsapp_react? +

Yes. Add a rate_limit block to the whatsapp_react 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 whatsapp_react completely? +

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

whatsapp_react is provided by the Waha MCP server (@marcos-heidemann/waha-mcp-server). PolicyLayer sits as a proxy in front of this server to enforce policies before tool calls reach the server.