How do spiders know when it's time to re-index a page?

Question

CMS

I am making an online store. It has quite a few items. Writing full-fledged texts for everyone is too long and dreary, so I decided to first start all products with a brief formal description, and only then, at my leisure, gradually add detailed texts written with SEO in mind, meta-keywords and all that. I would not want the search engines to remember the descriptions of the goods forever the way I do them now - it would be desirable to re-index as the information is replenished. How can you make them understand? Maybe there is some kind of meta tag or something that shows the update date to the spiders, for example?

Answer 1

There are directives in the sitemap but in practice they are ignored by search engines.
Sometimes search engines take into account the file modification date in the headers, but not always either.
In general, search engines download all pages in 1-2 weeks.