What is the maximum size of the body in the conversation reply endpoint?

Regarding this endpoint - https://developers.intercom.com/intercom-api-reference/reference/reply-to-a-conversation

Is there a limit to the size for body? If there is, what is that limit? We want to be able to send a transcript of previous conversations to the agent but we were wondering if there is limit to the length of the body that we can send in the payload in a single call.