Sending Messages
Sending messages is a core part of an agent's functionality. With all activity handlers, a send method is provided which allows your handlers to send a message back to the user to the relevant conversation.
app.on('message', async ({ activity, send }) => {
await send(`You said: ${activity.text}`);
});
In the above example, the handler gets a message activity, and uses the send method to send a reply to the user.
app.on('signin.verify-state', async ({ send }) => {
await send('You have successfully signed in!');
});
You are not restricted to only replying to message activities. In the above example, the handler is listening to signin.verify-state events, which are sent when a user successfully signs in.
This shows an example of sending a text message. Additionally, you are able to send back things like adaptive cards by using the same send method. Look at the adaptive card section for more details.
Streaming​
You may also stream messages to the user which can be useful for long messages, or AI generated messages. The SDK makes this simple for you by providing a stream function which you can use to send messages in chunks.
app.on('message', async ({ activity, stream }) => {
stream.emit('hello');
stream.emit(', ');
stream.emit('world!');
// result message: "hello, world!"
});
Streaming is currently only supported in 1:1 conversations, not group chats or channels

@Mention​
Sending a message at @mentions a user is as simple including the details of the user using the addMention method
app.on('message', async ({ send, activity }) => {
await send(new MessageActivity('hi!').addMention(activity.from));
});
Targeted Messages​
Targeted messages are currently in preview.
Targeted messages, also known as ephemeral messages, are delivered to a specific user in a shared conversation. From a single user's perspective, they appear as regular inline messages in a conversation. Other participants won't see these messages, making them useful for authentication flows, help or error responses, personal reminders, or sharing contextual information without cluttering the group conversation.
To send a targeted message when responding to an incoming activity, use the withRecipient method with the recipient account and set the targeting flag to true.
import { MessageActivity } from '@microsoft/teams.api';
app.on('message', async ({ send, activity }) => {
// Using withRecipient with isTargeted=true explicitly targets the specified recipient
await send(
new MessageActivity('This message is only visible to you!')
.withRecipient(activity.from, true)
);
});