The WhatsApp messaging API brings tags and metadata in line with the rest of the platform. When you [send a WhatsApp message](/docs/api/reference/send-whats-app-message), you can now attach:

- **Tags**: structured `{name, value}` labels, up to 20 per send, for low-cardinality dimensions like `category` or `experiment_variant`
- **Metadata**: an arbitrary JSON object (up to 2 KB) for your own per-send context, such as internal IDs

Both are echoed back on the message resource and on [list results](/docs/api/reference/list-whats-app-messages), which also gain a `tag` query parameter to filter by tag name or an exact `name:value` pair, matching the filtering already available for email and SMS messages.