We have a text heavy, high quality and original content online manual for our software:http://www.scirra.com/manual/1/construct-2I was about to embark on entering meta descriptions for these pages.  However the thought crossed my mind, is it necessary for these pages?Google seems to be quite good at picking relevant snippets out, and I wouldn't want to convolute the process of searching and discovering these pages with meta tags that will be sub par to the snippet Google would have otherwise served.Is purposefully not entering a meta description on these pages a good idea?  Or am I being an idiot?  They just don't seem necessary for these pages, and also they would be difficult to write for.
Meta descriptions for manual
seo;content;meta description
It can't hurt - unless the time invested in writing meta descriptions is prohibitive.Google's creation of sites' titles and descriptions (or snippets) is  completely automated and takes into account both the content of a page  as well as references to it that appear on the web.We use a number of different sources for this information, including  descriptive information in the META tag for each page.-Improve snippets with a meta description makeover at Google Webmaster CentralWhenever a user searches on a term which appears in the manual, Google will probably display a snippet of text from within the document rather than relying upon the meta description.If you anticipate many other web pages linking to pages within your manual (in which case a user's non-specific search is more likely to pull up meta description contents) it makes sense to put together a meta description but, if you anticipate few incoming links (in which case users will likely be searching on specific terms which appear within your manual) you can probably hold off on drafting meta descriptions and let Google use the manual's contents for its snippets.