Request for full manuscript?

It means they want to read the entire book. I've had a full request, and no, it didn't lead to an offer of representation. Which is to say, "sometimes, but not always."

It's a good sign that your query and sample chapters are strong enough that the agent (or their assistent--whoever's reading that stuff) wants to read more. But it's not a guarantee that they'll like the whole thing.

What Rhoda said.

On querytracker you can see how often an agent requests fills and how often those turn into offer. some agents request everything, others are pickier.

Your odds of getting an agent are better if you get a lot of requests for a full, but it's by no means guaranteed. Just like having an agent ups your chance of publication, but doesn't guarantee you'll get picked up by a publisher. There are a lot of variables, and only some of them relate to how good the book is (like how easy will it be to sell? Is there another book set to come out that's very similar? Is there a clear audience, or is it so niche that only a handful of people might read it? The list goes on.)

Well I'd say it could bump up your chances, but you can't look into it like that. You might have a great query and a great hook. But your execution of the story isn't what they thought. Or perhaps your writing isn't as strong as they'd want.

However, on the more positive hand, it could be exactly what they were looking for and asking for a full could be their way of wanting to read the whole thing asap. Once they have it, they can read it all in one sitting and offer rep!

If you're getting full requests, your query's working for some people's tastes Congrats.