Wassenger messaging

Wassenger Messaging

Send any kind of WhatsApp message through Wassenger — the agent picks free-form vs template automatically based on the 24-hour rule, and uploads media correctly.

When to use

• The user asks to send a message, reminder, confirmation, notification, or alert to a WhatsApp number.
• The user wants to schedule a message for later or send a poll.
• The user asks "how do I send a template?" or hits a 24-hour-window error from another skill.
• A higher-level industry skill (wassenger-ecommerce, wassenger-restaurants, …) calls down here for the actual send.

If the user wants to broadcast to many contacts at once, route to wassenger-campaigns — campaigns have batching, scheduling, and quota controls that single-message sends do not.

Prerequisites

• wassenger-setup complete (API key + MCP installed).
• At least one device with status: ready — fetch with get_whatsapp_devices if you don't have its ID yet.
• For media: either a public URL or a previously-uploaded file.id (see Recipe 3).

The 24-hour rule (read this first)

Every send falls into one of two modes:

Mode	When it applies	Tool to call
Free-form	The recipient sent a message to this device in the last 24 hours.	send_whatsapp_message with action:"text" / "media" / "poll" / etc.
Template	The last inbound message is older than 24 hours, or no prior conversation exists.	send_whatsapp_message with action:"template" + template: { name, language, body, … }.

Decision flow:

1. Get the chat: get_whatsapp_chat_by_id (or fall back to search_whatsapp_chats_by_name).
2. Inspect chat.lastInboundAt. If absent or > 24 h ago → use a template.
3. Otherwise → free-form.

List approved templates with list_whatsapp_templates before sending — only templates with status: APPROVED work, and you must match the language of the template (e.g., es, en_US, pt_BR).

Recipes

Recipe 1 — Send a plain text message

"Send 'Tu pedido #1234 está listo para recoger' to +34 600 111 222 from my main device."

1. get_whatsapp_devices → pick the ready device, store device.id
2. (optional) verifyWhatsAppNumberExists with the phone (takes E.164, e.g. "+34600111222")
3. send_whatsapp_message
   - device: <device.id>
   - action: "text"
   - chat: "[email protected]"
   - message: "Tu pedido #1234 está listo para recoger"

Report back the returned message.id so the user can track delivery.

Recipe 2 — Send a media message (PDF receipt)

"Send this PDF receipt to my client +1 555 0100."

If the user has a public URL:

send_whatsapp_message
  - device: <id>
  - action: "media"
  - chat: "[email protected]"
  - media: { url: "https://example.com/receipt.pdf" }
  - message: "Here is your receipt"  # optional caption — there is no `caption` param

If they have a local file, upload it first:

1. upload_whatsapp_file_from_url with the public URL
   → returns file.id
2. send_whatsapp_message with action: "media", media: { file: <file.id> }

Supported media: images (jpg/png/webp), audio (ogg/mp3), video (mp4), documents (pdf, docx, xlsx, txt, …). Approximate WhatsApp limits: images ~5 MB, audio ~16 MB, video and documents up to ~100 MB (uploaded via resumable upload).

Recipe 3 — Send a WABA template (outside the 24h window)

"Remind everyone who has a reservation tomorrow at 8pm."

Assuming a reservation_reminder template approved in Spanish with variables {{1}}=customer_name, {{2}}=time:

1. list_whatsapp_templates with device + status=APPROVED
   → confirm "reservation_reminder" exists
2. For each contact:
   send_whatsapp_message
     - device: <id>
     - action: "template"
     - chat: <contact.wid>            # e.g. "[email protected]"
     - template:
         name: "reservation_reminder"
         language: "es"
         body: [{ name: "1", value: contact.name }, { name: "2", value: "20:00" }]

If the template has a header image or a dynamic button, populate template.header and template.button[] (not Meta-style components). The header takes { media: { url, type } }, { text: { name, value } }, or { location: {…} }; each button is { type, position, name, value }. There is no top-level buttons parameter. list_whatsapp_templates returns the expected variables per template.

Recipe 4 — Schedule for later

"Schedule a Good Morning message to my list at 8am tomorrow."

Use action:"scheduled" with deliverAt (ISO 8601) — or delay (seconds) / delayTo ("1h"). deliverAt is only valid with the scheduled action:

send_whatsapp_message
  - device: <id>
  - action: "scheduled"
  - chat: "[email protected]"
  - message: "Good morning! ☀️"
  - deliverAt: "2026-05-28T08:00:00+02:00"

Wassenger queues the message and dispatches it at the requested time. Use manage_whatsapp_queue with action:"get_status" to verify it landed in the queue.

Recipe 5 — Send a poll

"Ask my customer Marta which day works better — Friday, Saturday or Sunday."

send_whatsapp_message
  - device: <id>
  - action: "poll"
  - chat: "[email protected]"
  - poll:
      question: "Which day works for you?"
      options: ["Friday", "Saturday", "Sunday"]
      multipleAnswers: false   # set true to allow more than one selection

Polls are supported on the WABA Cloud API. Read poll results later with get_whatsapp_chat_messages action=by_type and messageTypes:["poll"]. Confirm your device is on a Cloud-API-compatible plan if polls don't appear — older WABA on-premise hosting may not support them.

Recipe 6 — Reply / react / forward

"React with 👍 to the last message from +34 600 111 222."

1. get_whatsapp_chat_messages with chat=<chat.wid>, action=recent, limit=1
2. manage_whatsapp_message_interactions
   - chat: <chat.wid>
   - action: "reaction"
   - reactionMessage: <last.id>
   - reaction: "👍"          # use "-" to remove a reaction

Other actions: reply (threaded reply — quote = the message ID to reply to, plus message) and forward (to another chat). There is no delete-message operation in the MCP.

Common pitfalls

• Sending free-form outside 24 h. Returns 131047 from Meta. Switch to a template or wait for the customer to reply first.
• Template variables out of order. {{1}} in the template == the entry with name: "1" in template.body[]. Mismatched names will deliver gibberish.
• Forgetting action or device. action selects what kind of message you send; device is needed when the account has more than one number. Missing either commonly trips a 400.
• Recipient format. The recipient field is chat — a WhatsApp ID / WID such as [email protected] (digits + @c.us, no + or spaces). There is no phone parameter on send_whatsapp_message. (verifyWhatsAppNumberExists is the exception — it takes an E.164 phoneNumber.)
• Media URL not reachable. Wassenger fetches the URL server-side. If it returns 403/404 or requires auth, upload via upload_whatsapp_file_from_url after first making it public, or proxy through your own server.
• Marketing copy in a Utility template. Meta categorizes templates at approval time. Sending marketing through a Utility template gets the template (and potentially the WABA) suspended on review. Use the right category from the start.

See also

• wassenger-mcp — tool catalog if you need exact parameter shapes (references/tools-reference.md).
• wassenger-campaigns — for sends to many contacts.
• wassenger-inbox — once messages arrive, manage the resulting chats.
• wassenger-webhooks — receive message:delivered, message:read, message:reply events in real time.