Reference

WA Lookup MCP reference

The Model Context Protocol is an open standard that lets AI applications call external tools during a conversation. Once connected, you can ask your assistant to check a number or review a batch without writing a separate API integration.

MCP is a protocol adapter, not a separate validation system. It uses the same products, balance, billing, concurrency limits, timeouts, and result semantics as the REST API.

Products, pricing and limits are in the API reference

Authentication

Use the exact same API key you use for the REST API. Create or copy it from Settings, then add it as a Bearer token in your MCP client configuration.

Authorization header

Authorization: Bearer YOUR_API_KEY

Keep your API key privateOnly add the key to your own trusted client configuration. Never paste it into a public prompt, commit it to source control, or expose it in browser code.

Server URL

The server uses the official Streamable HTTP transport. Point your client to this single endpoint; no local MCP process is required.

Item	Value
MCP endpoint	https://walookup.com/mcp
Streamable HTTP	Requests use JSON-RPC over Streamable HTTP and are authenticated by the same API-key middleware as the REST endpoints.

Connect your client

We support Claude Code, Cursor / Claude Desktop, and any other MCP client that speaks Streamable HTTP. Pick the matching tab below and replace the placeholder with your API key.

claude mcp add --transport http wachecker https://walookup.com/mcp --header "Authorization: Bearer YOUR_API_KEY"

Add the remote server from your terminal.

{
  "mcpServers": {
    "wachecker": {
      "url": "https://walookup.com/mcp",
      "headers": {
        "Authorization": "Bearer YOUR_API_KEY"
      }
    }
  }
}

Add this server entry to the client's MCP configuration.

Available tools

The tools are scoped to the app that owns your API key. Call list_products first when you need to discover valid product codes.

list_products

Lists the products available to this API key, including prices, billing multipliers, purposes, and response fields.

Parameters

No parameters

check_number

Checks one submitted number synchronously. registered is the primary result; avatar and business are optional product fields.

Parameters

service_type · string · required
identifier · string · required

check_numbers

Checks 1–100 numbers with one service_type. Results preserve input order; each number is evaluated independently and a failed number does not stop the rest.

Parameters

service_type · string · required
identifiers · string[] · required · max 100

get_balance

Reads the current account balance. It is read-only and does not create a check or charge the account.

Parameters

No parameters

Example prompts

After connecting, ask your assistant in plain language:

Check whether +17253100591 is registered on WhatsApp.
Check these 20 numbers and summarize registered versus unregistered results.
Show the products available to my API key and their prices.
How much balance is left before I run this batch?

Error handling

Tool failures are returned with isError=true so the client can explain what happened instead of treating the connection as broken. Business failures use the same code, msg, data contract as the API.

Example tool error

{
  "code": 42901,
  "msg": "too many concurrent requests",
  "data": null
}

Code	Description
`40000`Invalid product or field	Unsupported service_type or conflicting fields.
`40002`Invalid number	The submitted number is not a valid format.
`40100`Missing or invalid API key	Check the Bearer header and confirm the key is active.
`40200`Insufficient balance	The request is rejected before processing when the full batch amount cannot be covered.
`42200`Undetermined	The number could not be determined at this time. No result is returned, and this call is not charged.
`42901`Concurrency budget full	All five in-flight request slots are busy, or a multi check is already running on this account. Not charged; retry once one finishes.
`50303`Service at capacity	Too many checks are in progress platform-wide. Not charged; wait for the Retry-After seconds and resubmit.
`50400`Check timed out	Did not finish in time. Not charged; a timed-out multi check fails as a whole and is refunded in full.
`50300`Service maintenance	Retry later.