Building chatbots: Why message length matters

4 min read
Ish Jindal
  •  Jul 17, 2017
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When people ask me why they should use a bot instead of a form or website, my immediate response is that chatbots are more engaging than conventional means of communication.Twitter Logo At the crux of this argument is an innocuous characteristic of chat that most people take for granted: message length.

Why is message length important?

A chatbot feels more engaging than a piece of static content (like a website or a form) because it prompts the user to take action within a few seconds of the user landing on the bot. With a webpage, on the other hand, the user has to get their bearings, read a bunch of options and text, and then take action. One reason for this is because a chat interface is familiar and a user knows where to look when they encounter a bot.

Related: The ultimate guide to chatbots

The second and equally important reason is message length. Since messages tend to be shorter than the amount of text on regular websites, a user doesn’t have to read as much before taking action.

“Chatbots are more engaging than conventional means of communication.”

Twitter Logo

Look at this insurance company landing page:

And compare it to the first couple of messages of this insurance-buying chatbot:

The short messages of the bot prompt the user to act immediately where the page requires more reading.

By the same token, having a long initial message would completely nullify the user engagement that a bot offers because a user has to spend time reading and scrolling through the long message:

These rules hold true later in the conversation as well. The reason short messages are better in your chatbot isn’t just so you can hook the user at the beginning—it’s also because of the unique structure of the chat interface. Chat as a medium is optimized for short bursts of text.Twitter Logo The message bubbles in most messengers (and in Tars bots) stick to the side of the screen (left for the bot and right for the user), leaving a margin in which text cannot be displayed. As such, what long messages lose in width they must make up for in height, causing them to look like large, cramped blocks of text that are unpleasing to the eye:

Best practices

So how do you decide length of your messages? Here are a few tips:

The first set of messages should be short

Make the first few messages of your bot shortTwitter Logo, and then try to hook your users with a question. Strategic Design Hub’s Tars bot is a perfect example of this (check it out here):

Their first gambit as a question is intriguing and connects to the message of their flow.

Twitter rule

To prevent my messages from getting too long, I generally follow the Twitter rule and keep my messages the size of a tweet. Smartphones and the internet have made instant gratification easily accessible for most of your users. So your bot shouldn’t take more effort to interact with than scrolling through a Twitter or Instagram feed.

“Interacting with a bot should be as easy as scrolling through Instagram.”

Twitter Logo

Don’t stick to the Twitter rule

Contradictory, I know. The Twitter rule is a reference but you do have some wiggle room on either side—and in some cases, a longer message makes sense. For example, when I want to send users a schedule for an event, I find it easier to send one long message so that they have a schedule they can screenshot.

Testing, testing, testing…

If you didn’t read last week’s best practices, go read the post—and get used to this point because it will come up in pretty much everything. Start with the Twitter rule, make adjustments where you feel necessary, and then test, test, test. The message length that you like to receive is probably close to the message length that most people like. Once you’ve tested it a few times and you’re happy with how the messages look and read, hand it to someone else and have them look at it with fresh eyes.


  • Message length is a significant contributor to the high user engagement of bots
  • When a user lands on a bot, the bot prompts the user to take action within a few seconds. On a website, users need to get their bearings, read all the text, and figure out what’s happening
  • A reason for this is that the initial prompt in a bot is a short burst of text
  • Making a message too long diminishes the level of engagement a bot offersTwitter Logo, as users have to spend more time reading
  • This is true later in the messaging flow as well
  • Messages that are too long can look cramped and require scrolling to read because of the way the chat UI is structured
  • To get around these problems, keep the first few messages short and sweet
  • Later messages can be slightly longer but try to keep them short unless it’s absolutely unavoidable to write a long message
  • A good reference point is the Twitter rule (keep each message under 140 characters)

Agree with these pointers? Disagree? Maybe there’s something we missed. Let us know on Twitter.

Header image by Michelle M. F. CC BY-SA 2.0.

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