To say that a summary is important to a work of fiction — or, indeed, any work in general — is an understatement. The summary is almost certainly the first thing your prospective reader will see; it is where they go to know what the work is about and to get some idea of whether they will want to read it or not. You are essentially making a pitch for their time (and money, if you're writing professionally), so your summary is a vital way of letting them know that spending it on your work won't be a waste. So making the first thing that your reader sees a statement declaring that you aren't any good at an essential part of writing is a bit like introducing yourself to a prospective partner at a blind-date by saying that you're terrible at introducing yourself and then proceeding to list all your worst character flaws.
It is safe to say that most (though, in the interests of strict fairness, not all) online works described in this fashion aren't very good. Furthermore, such stories usually die long before they are completed, due to the author giving up from lack of feedback. Neither is surprising; if the author lacks the skill to write a proper summary, the story itself usually doesn't fare any better.
Sometimes followed with "please read and review", although most fanfic readers take this phrase as an ominous warning and end up not even reading the fanfic, let alone giving any feedback. Sometimes, the phrase is substituted with "Summary sucks, story is much better", but most readers will react in the same way as before.
"I Suck at Summaries" should be avoided since it tells readers that either the author doesn't have any self-confidence, or that the story is so boring that the author couldn't be bothered to put in a real summary. Or worse, that the author doesn't suck at summaries so much as they suck at writing in general. After all, if the author can't even write a basic two-sentence summary, then why should the reader have any confidence in their ability to create a longer narrative? It also shows a failure of Show, Don't Tell: don't use the summary to say the summary is rubbish - write a better one that actually summarizes the entire story.
Some writers attempt to justify this when on websites like fanfiction.net where the summary limit is under 500 characters by saying they don't have enough space. This isn't much of an argument, since the whole purpose of a summary is to establish what the story is about in a concise manner without revealing too much of the plot; long summaries defeat the whole point. Giving an eloquent summary of your story in a short space is actually a show of good writing. Besides, 500 characters isn't that short.note
It should be noted in the interests of fairness both that Tropes Are Tools and writing a good summary can be legitimately hard, especially for an inexperienced writer (as many fanfic writers tend to be). This is especially the case if your story is complex or is a Long Runner or Door Stopper — the question becomes a matter of what to include in the summary and what to leave out so that you're both giving a clear sense of what the story is about while not saying too much. It is also worth remembering that creative writing and summarising are different skills, and it is entirely possible to be better at one rather than the other. However, fair or otherwise, this phrase acts as a red-flag to the reader, and so is best avoided; as noted, the purpose of a summary is to give the reader reasons to want to read the story, not reasons not to want to read it. If you're not very good at summaries, then, it's better to practice and get better at them rather than complain that you find them hard and no one wants to read your work.
In the interests of being helpful, therefore, we at TV Tropes would like to offer you a few suggestions if summarising your story is something you struggle with:
- Think about what the main "beats" of the narrative are; what are the absolutely essential things that happen? Focus on those. Your reader doesn't necessarily need to know about the conversations your protagonist has with their landlord about the rent every morning, but if your protagonist is going to be solving a murder in the story then that's probably something the reader should know about.
- In particular, think about what the inciting incident of the story is — where does your story essentially start? Focussing on this will help give your reader a flavour of what the story is about while at the same time not revealing too much about what happens later in the narrative (and thus spoiling the surprise). Don't spoil the third-act twist that Granny was the murderer in your summary, but by all means tell them that the protagonist's troubles start when an old Love Interest re-enters their life.
- What kind of genre is your story predominantly? What kind of mood do you want to set for your reader? Think about how you want your reader to react when reading the story and frame the summary around that. If your story is primarily horror, you probably don't want your reader going into it thinking it's going to be a romantic comedy (unless you really want to surprise them, but that's a tricky needle to thread and is likely to risk backfiring and annoying the reader, which isn't going to help you; if you're inexperienced, it's probably better to be more upfront at first).
- Keep it short. Frankly, it doesn't matter how long the story is, how much complex it is, or how much space you have to write it — the purpose of a summary isn't to tell your reader everything that happens, it's simply to provide a brief overview of the essential details of what the story is about, and/or to offer a tantalizing reason for the reader to want to read the whole thing. You actually don't want to give away everything that happens in the story, since if the reader wants to know everything that happens they can just, well, read the story.
- Practice by summarising other films, books, TV shows, etc. Boil them down to their essential components and see if you can summarise them in as few words/sentences as possible while making them intriguing. As an example:
Ultimately, avoid using this phrase as much as possible. It's not going to help.