Check multiple phone numbers at once to see if they are registered on WhatsApp.
AI agents call whatsapp_bulk_check_users to retrieve information from WSAPI WhatsApp MCP Server without modifying anything — typically the context-gathering step in research, monitoring, and reporting workflows, before the agent takes action elsewhere.
This tool performs a read-only query against WhatsApp's database to determine user registration status. It retrieves information without modifying, executing code, deleting data, or making financial transactions. The blast radius of misuse is limited—an AI could discover if specific phone numbers are WhatsApp users, which has minor privacy implications but no destructive consequences.
From the tool's definition Tool description: 'Check multiple phone numbers at once to see if they are registered on WhatsApp.' The verb 'check' indicates a query operation that retrieves whether users exist on the platform.
Attacks that exploit this kind of access
Check multiple phone numbers at once to see if they are registered on WhatsApp. It is categorised as a Read tool in the WSAPI WhatsApp MCP Server MCP Server, which means it retrieves data without modifying state.
Register the WSAPI WhatsApp MCP Server MCP server in PolicyLayer and add a rule for whatsapp_bulk_check_users: 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 WSAPI WhatsApp MCP Server. Nothing to install.
whatsapp_bulk_check_users is a Read tool with low risk. Read-only tools are generally safe to allow by default.
Yes. Add a rate_limit block to the whatsapp_bulk_check_users 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.
Set action: deny in the PolicyLayer policy for whatsapp_bulk_check_users. 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.
whatsapp_bulk_check_users is provided by the WSAPI WhatsApp MCP Server MCP server (wsapi-chat/wsapi-mcp). PolicyLayer sits as a proxy in front of this server to enforce policies before tool calls reach the server.
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