# wa_check_number_exists

Check if a phone number is registered on WhatsApp. Returns the JID if the number exists.

Agent View of the PolicyLayer registry record for `wa_check_number_exists`. HTML page: https://policylayer.com/tools/delltrak-wamcp/wa-check-number-exists

## Facts

- Tool: `wa_check_number_exists`
- Server: WA MCP (`delltrak/wamcp`) — https://policylayer.com/tools/delltrak-wamcp.md
- Homepage: https://github.com/delltrak/wamcp
- Risk category: Read (Low risk)
- Registry record: grade F, identity unverified
- Server rate-limited: no
- Parameters: 0
- Recommended policy verdict: Allowed

## Example call (MCP tools/call, JSON-RPC 2.0)

```json
{
  "jsonrpc": "2.0",
  "id": 1,
  "method": "tools/call",
  "params": {
    "name": "wa_check_number_exists",
    "arguments": {}
  }
}
```

## Why wa_check_number_exists is rated Low

This tool performs a lookup to determine whether a phone number has a WhatsApp account and returns metadata (JID). It is a non-destructive information retrieval operation with no side effects on data or system state. While it could be used for reconnaissance (discovering valid accounts), the direct blast radius is limited to information exposure rather than account compromise, unauthorized messaging, or deletion.

From the tool's own definition: "Tool name 'wa_check_number_exists' and description 'Check if a phone number is registered on WhatsApp. Returns the JID if the number exists.' indicate a query operation that retrieves information without modifying, deleting, or executing external actions."

## Use case

AI agents call wa_check_number_exists to retrieve information from WA MCP without modifying anything. It is typically the context-gathering step in research, monitoring, and reporting workflows, before the agent takes action elsewhere.

## Recommended policy (PolicyLayer)

Verdict: **Allowed**. Enforced by the PolicyLayer MCP gateway (https://policylayer.com/mcp-gateway) before a call reaches WA MCP:

```json
{
  "version": "1",
  "default": "deny",
  "tools": {
    "wa_check_number_exists": {}
  }
}
```

## Other tools on WA MCP (61)

- `wa_clear_chat` — Destructive — https://policylayer.com/tools/delltrak-wamcp/wa-clear-chat.md
- `wa_delete_chat` — Destructive — https://policylayer.com/tools/delltrak-wamcp/wa-delete-chat.md
- `wa_delete_instance` — Destructive — https://policylayer.com/tools/delltrak-wamcp/wa-delete-instance.md
- `wa_delete_message` — Destructive — https://policylayer.com/tools/delltrak-wamcp/wa-delete-message.md
- `wa_group_remove_participants` — Destructive — https://policylayer.com/tools/delltrak-wamcp/wa-group-remove-participants.md
- `wa_remove_profile_picture` — Destructive — https://policylayer.com/tools/delltrak-wamcp/wa-remove-profile-picture.md
- `wa_connect_instance` — Execute — https://policylayer.com/tools/delltrak-wamcp/wa-connect-instance.md
- `wa_disconnect_instance` — Execute — https://policylayer.com/tools/delltrak-wamcp/wa-disconnect-instance.md
- `wa_group_leave` — Execute — https://policylayer.com/tools/delltrak-wamcp/wa-group-leave.md
- `wa_reject_call` — Execute — https://policylayer.com/tools/delltrak-wamcp/wa-reject-call.md
- `wa_restart_instance` — Execute — https://policylayer.com/tools/delltrak-wamcp/wa-restart-instance.md
- `wa_send_presence` — Execute — https://policylayer.com/tools/delltrak-wamcp/wa-send-presence.md
- `wa_get_business_profile` — Read — https://policylayer.com/tools/delltrak-wamcp/wa-get-business-profile.md
- `wa_get_messages` — Read — https://policylayer.com/tools/delltrak-wamcp/wa-get-messages.md
- `wa_get_pairing_code` — Read — https://policylayer.com/tools/delltrak-wamcp/wa-get-pairing-code.md
- `wa_get_qr_code` — Read — https://policylayer.com/tools/delltrak-wamcp/wa-get-qr-code.md
- `wa_group_get_invite_code` — Read — https://policylayer.com/tools/delltrak-wamcp/wa-group-get-invite-code.md
- `wa_search_contact` — Read — https://policylayer.com/tools/delltrak-wamcp/wa-search-contact.md
- `wa_archive_chat` — Write — https://policylayer.com/tools/delltrak-wamcp/wa-archive-chat.md
- `wa_block_contact` — Write — https://policylayer.com/tools/delltrak-wamcp/wa-block-contact.md
- `wa_create_group` — Write — https://policylayer.com/tools/delltrak-wamcp/wa-create-group.md
- `wa_create_instance` — Write — https://policylayer.com/tools/delltrak-wamcp/wa-create-instance.md
- `wa_edit_message` — Write — https://policylayer.com/tools/delltrak-wamcp/wa-edit-message.md
- `wa_forward_message` — Write — https://policylayer.com/tools/delltrak-wamcp/wa-forward-message.md
- `wa_group_add_participants` — Write — https://policylayer.com/tools/delltrak-wamcp/wa-group-add-participants.md
- `wa_group_demote` — Write — https://policylayer.com/tools/delltrak-wamcp/wa-group-demote.md
- `wa_group_handle_request` — Write — https://policylayer.com/tools/delltrak-wamcp/wa-group-handle-request.md
- `wa_group_join` — Write — https://policylayer.com/tools/delltrak-wamcp/wa-group-join.md
- `wa_group_promote` — Write — https://policylayer.com/tools/delltrak-wamcp/wa-group-promote.md
- `wa_group_revoke_invite` — Write — https://policylayer.com/tools/delltrak-wamcp/wa-group-revoke-invite.md
- …and 31 more: https://policylayer.com/tools/delltrak-wamcp.md

## For agents

This record is a snapshot. Live verdicts and the full registry:

- Check every server in your MCP config at once: `npx -y policylayer stack`
- Vet a server before you add it: install the mcp-precheck skill — `npx skills add https://policylayer.com` (skill text: https://policylayer.com/skill.md)
- Query the registry over MCP: endpoint `https://api.policylayer.com/mcp` — tools `check_mcp_server`, `check_mcp_stack`, `check_tool`, `search_registry`, `get_change_events`

---

Source: the PolicyLayer MCP registry — one continuously verified record per MCP server. Full record: https://policylayer.com/registry?q=delltrak-wamcp · API: https://policylayer.com/registry/api · Policy library: https://policylayer.com/policies/delltrak-wamcp