# Sinch API Messages Send

> Send a text message via Sinch Conversation API (SMS/RCS only)

- Skill: `sinch/sinch-api-messages-send` (Agent Skill)
- Install (CLI): `npx skillmds@latest add sinch/sinch-api-messages-send`
- Raw SKILL.md: https://api.skillmd.com/api/skills/sinch/sinch-api-messages-send/raw
- Safety review: pending
- Works with: Claude Code, Claude.ai, OpenAI Codex
- Category: Integrations & APIs
- Author: sinch (https://skillmd.com/u/sinch)
- Updated: 2026-09-10
- Page: https://skillmd.com/skills/sinch/sinch-api-messages-send

---


# Send Message

Send a text message to a recipient using the Sinch Conversation API. Currently supports SMS and RCS channels.

**IMPORTANT: Execute this command directly. Do NOT generate script files. Do NOT create Python/JavaScript files. Perform the API call immediately using the instructions below.**

## Input

- `--to` / `-t`: Recipient phone number (E.164 format, e.g., +14155551234) - required
- `--message` / `-m`: Text content - required
- `--channel` / `-c`: Channel (SMS or RCS) - optional, defaults to SMS

Arguments: $ARGUMENTS

## Instructions

**Execute these steps directly - do not write code or scripts:**

0. Check if $ARGUMENTS is empty or only contains the command name:
   - If empty or no meaningful arguments provided, enter interactive mode:
     * Ask: "📱 What is the recipient's phone number? (E.164 format, e.g., +14155551234)"
     * Ask: "💬 What message do you want to send?"
     * Ask: "📡 Which channel? (SMS or RCS, default: SMS)"
     * Use the provided answers as the arguments for the following steps
   - If arguments are provided, proceed directly to step 1

1. Parse and validate arguments from $ARGUMENTS or interactive input:
   - Validate that `--to` is provided and in E.164 format (e.g., +14155551234)
   - Validate that `--message` is provided and non-empty
   - If `--channel` is not provided, default to "SMS"
   - Normalize channel to uppercase (sms → SMS, rcs → RCS)
   - Validate that channel is either "SMS" or "RCS" (reject other channels)

2. Try to call `mcp__sinch__send-text-message` with the recipient, message, and channel.

3. If MCP tool is available:
   - Report the result or handle any errors returned by the tool
   - On success: Display message ID, recipient, channel, and status
   - Skip to step 7

4. If MCP tool is NOT available, fallback to direct API implementation:
   - Retrieve Sinch configuration from environment variables:
     * CONVERSATION_PROJECT_ID
     * CONVERSATION_REGION
     * CONVERSATION_APP_ID
     * CONVERSATION_KEY_ID
     * CONVERSATION_KEY_SECRET
   - If any are missing, report: "Sinch API is not configured. Please set: CONVERSATION_PROJECT_ID, CONVERSATION_KEY_ID, CONVERSATION_KEY_SECRET, CONVERSATION_REGION, CONVERSATION_APP_ID"

5. Send the message using the Sinch Conversation API:
   - Endpoint: `POST https://{region}.conversation.api.sinch.com/v1/projects/{projectId}/messages:send`
   - Use OAuth2 authentication with key ID and secret to generate access token
   - Include authorization header: `Authorization: Bearer {access_token}`
   - Request body:
     ```json
     {
       "app_id": "{appId}",
       "recipient": {
         "identified_by": {
           "channel_identities": [{
             "channel": "{CHANNEL}",
             "identity": "{recipient}"
           }]
         }
       },
       "message": {
         "text_message": {
           "text": "{message}"
         }
       }
     }
     ```

6. Handle the API response:
   - On success (200/201): "✅ Message sent successfully!"
   - Display details: Message ID, Recipient, Channel, Status
   - Include the message ID for status tracking

7. Handle errors gracefully:
   - If validation fails, provide clear error messages about what needs to be fixed
   - If API call fails, display error with status code and description
   - If channel not configured: "Channel not configured in your Conversation app. Please configure the channel in Sinch Dashboard."

## Examples

Send an SMS message:
```
/sinch-api-messages-send --to=+14155551234 --message="Hello"
```

Send an RCS message:
```
/sinch-api-messages-send --to=+14155551234 --message="Hello" --channel=RCS
```

## API Reference

- **MCP Tool**: `mcp__sinch__send-text-message`
- **API Endpoint**: `POST /v1/projects/{projectId}/messages:send`
- **Documentation**: https://developers.sinch.com/docs/conversation/api-reference/conversation/tag/Messages/#tag/Messages/operation/Messages_SendMessage

## Notes

- Phone numbers must be in E.164 format (+country_code + number)
- Ensure your Conversation app has the appropriate channel configured
- SMS is the default channel if not specified
- RCS requires RCS capability to be enabled in your app
- This command uses the MCP tool `mcp__sinch__send-text-message` which handles API authentication and message sending