waha_send_message

THE RISK

Medium Risk

Why waha_send_message needs a policy

This tool creates/sends new messages, which is a reversible write operation (messages can be deleted via waha_delete_message). It modifies chat state by adding new messages. While it has communication side effects, it does not execute arbitrary code, delete data permanently, or involve financial transactions.

From the tool's definition Tool description explicitly states 'Send a text message to a WhatsApp chat' and 'Returns message ID and delivery timestamp'. The 'send' action creates new message data in WhatsApp chats.

Documented attack patterns abuse exactly the kind of access waha_send_message gives an agent:

POLICY

How to control waha_send_message

PolicyLayer is an MCP gateway — it sits between your AI agents and WAHA MCP Server, and nothing reaches the server without passing your rules. This is the rule we recommend for waha_send_message:

policy.json

{
  "version": "1",
  "default": "deny",
  "tools": {
    "waha_send_message": {
      "limits": [
        {
          "counter": "waha_send_message_rate",
          "window": "minute",
          "max": 30,
          "scope": "grant"
        }
      ]
    }
  }
}

waha_send_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.

Create a free account and register WAHA MCP Server — nothing to install.
Add this policy — paste it, or build it visually.
Point your MCP client (Claude, Cursor, anything) at your gateway URL.

LIMIT THIS TOOL →

Free to start. No card required.

EXPLORE

Related tools and policies

More WAHA MCP Server tools

Destructive waha_clear_chat_messages Clear all messages from a chat. WARNING: This is a destructive operation that cannot be un Destructive waha_delete_chat Delete a chat completely. WARNING: This is a destructive operation that cannot be undone. Destructive waha_delete_group_picture Remove group profile picture. Destructive waha_delete_message Delete a specific message from a chat. This is a destructive operation and cannot be undon Destructive waha_remove_group_participants Remove member(s) from a group. Requires admin privileges. Destructive waha_leave_group Leave a group. Execute waha_revoke_group_invite_code Revoke current invite link and generate a new one. Requires admin privileges. Write waha_demote_group_admin Remove admin privileges from participant(s). Requires admin privileges.

All 52 WAHA MCP Server tools →

Write tools on other servers

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Go deeper

The MCP Attack Database → Documented attack patterns against MCP deployments — and the policies that stop them.
Argument validation → Checking tool call arguments against schema and policy before they run.
Scoped token → Per-person credentials that grant a defined subset of servers and tools.
Rate Limiting MCP Tool Calls: A Practical Guide →
MCP Security: Why Prompt Guardrails Aren't Enough →

FAQ

Questions about waha_send_message

What does the waha_send_message tool do? +

Send a text message to a WhatsApp chat. Returns message ID and delivery timestamp. It is categorised as a Write tool in the WAHA MCP Server MCP Server, which means it can create or modify data. Consider rate limits to prevent runaway writes.

How do I enforce a policy on waha_send_message? +

Register the WAHA MCP Server MCP server in PolicyLayer and add a rule for waha_send_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 WAHA MCP Server. Nothing to install.

What risk level is waha_send_message? +

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

Can I rate-limit waha_send_message? +

Yes. Add a rate_limit block to the waha_send_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 waha_send_message completely? +

Set action: deny in the PolicyLayer policy for waha_send_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 waha_send_message? +

waha_send_message is provided by the WAHA MCP Server MCP server (seejux/waha-whatsapp-mcp). PolicyLayer sits as a proxy in front of this server to enforce policies before tool calls reach the server.

Enforce policy on every WAHA MCP Server tool call.

Start from WAHA MCP Server, add the rest of your stack, and see everything your agents can call. Then put policy on all of it.

CHECK YOUR STACK →