Message Reactions

Message reactions allow your agent to add or remove emoji reactions on messages in a Teams conversation, and to react to reactions added by users. This gives your agent a quick, low-friction way to acknowledge messages or signal status without sending a full text reply.

Adding a Reaction

To add a reaction to a message, use the reactions client through the API client:

app.OnMessage(async (context, cancellationToken) =>
{
    await context.Send("Hello! I'll react to your message.", cancellationToken);

    // Add a reaction to the incoming message
    await context.Api.Conversations.Reactions.AddAsync(
        context.Activity.Conversation.Id,
        context.Activity.Id,
        ReactionType.Like,
        cancellationToken: cancellationToken
    );
});

Removing a Reaction

You can also remove reactions that your agent has previously added:

app.OnMessage(async (context, cancellationToken) =>
{
    // First, add a reaction
    await context.Api.Conversations.Reactions.AddAsync(
        context.Activity.Conversation.Id,
        context.Activity.Id,
        ReactionType.Heart,
        cancellationToken: cancellationToken
    );

    // Wait a bit, then remove it
    await Task.Delay(2000, cancellationToken);
    await context.Api.Conversations.Reactions.DeleteAsync(
        context.Activity.Conversation.Id,
        context.Activity.Id,
        ReactionType.Heart,
        cancellationToken: cancellationToken
    );
});

Receiving Reactions

Your agent can also listen for reactions that users add or remove on messages in conversations it participates in. The activity carries ReactionsAdded and ReactionsRemoved collections.

.NET exposes a single OnMessageReaction handler plus dedicated OnMessageReactionAdded / OnMessageReactionRemoved sub-handlers.

app.OnMessageReactionAdded(async (context, cancellationToken) =>
{
    foreach (var reaction in context.Activity.ReactionsAdded ?? [])
    {
        Console.WriteLine($"User added reaction: {reaction.Type}");
    }
});

app.OnMessageReactionRemoved(async (context, cancellationToken) =>
{
    foreach (var reaction in context.Activity.ReactionsRemoved ?? [])
    {
        Console.WriteLine($"User removed reaction: {reaction.Type}");
    }
});

If you only need a single handler that runs for both adds and removes, use app.OnMessageReaction instead.

Available Reaction Types

The SDK ships a small set of named reaction constants for the most common reactions, exposed via the ReactionType class.

Any string-valued reaction ID is accepted, so you can pass any reaction ID from the Teams reactions reference page.

• ReactionType.Like — 👍
• ReactionType.Heart — ❤️
• ReactionType.Eyes — 👀
• ReactionType.CheckMark — ✅
• ReactionType.Launch — 🚀
• ReactionType.Pushpin — 📌

Skin Tones

Reactions tagged Diverse in the Teams reactions reference support five skin-tone variants. Append -tone1 through -tone5 to the reaction ID to select a variant:

1f44b_wavinghand-tone4

Rate Limits

Agents are limited to two reactions per second. Calls that exceed this limit are throttled and return a 429 response. Implement exponential backoff and honor the Retry-After header.

Best Practices

• Use reactions sparingly. Reactions work best when they signal something specific (acknowledgement, completion, an error). Reacting to every message creates noise.
• Match the reaction to the context. Different reactions carry different meanings. Choose one that aligns with your agent's purpose.
• Replace, don't stack. If your agent has already added a reaction and needs to update it, remove the existing reaction first, then add the new one. Adding a reaction that's already present is a no-op.
• Handle errors. Reaction operations can fail if the message no longer exists or the agent isn't a member of the conversation. Handle exceptions appropriately.

Differences from Feedback

Message reactions are different from the feedback feature:

• Reactions are quick emoji responses your agent adds to or removes from messages programmatically, and reactions users add to messages your agent can listen for.
• Feedback are interactive UI components (like/dislike buttons) that users can click to provide structured feedback on agent responses.

Use reactions when your agent wants to acknowledge or respond to a message with emoji. Use feedback when you want to collect user opinions about your agent's responses.