Dealing with changing return sizes

While at any given point in time a Stack Exchange site will have many different limits on data input sizes (tag length, markdown body length, user name length, etc.) the API does not document these. This is because they are subject to change at any time. Further complicating thing, many of these limits are in terms of characters of markdown so any change in a site's Markdown-to-HTML translation implicit changes the size of data returned in the API.

When faced with the choice of either returning variable length data or truncated data in the face of these changes, we've opted for the former. This can complicate using the API if your application persists data in a structured manner (such as a relational database). Developers must make a case-by-case decision whether to over allocate storage space in case API results increase in size, or truncate data.