What a meta description does
A meta description summarises a page in an HTML meta element. Google may use it as a search-result snippet when it provides a useful description for the query. Google can also select text from the page, so the submitted description is not guaranteed to appear.
The description tag is not a direct Google ranking signal. Its practical job is to describe the page accurately and help someone judge whether the result is relevant.
Write for the specific page
Explain what the reader will find and use the terminology appropriate to that page. Avoid repeating the same generic description across unrelated services or presenting a regional offer that the page does not support.
There is no universal character count that guarantees the whole description will display on every device and query. Keep it concise enough to be useful and make important information clear early.
Check the output
Review the actual HTML rather than only the CMS field. Confirm the description is present, readable and consistent with the visible content. A changed snippet does not by itself prove the tag is broken.
Sources
Google: writing useful meta descriptions and Google’s explanation of description and keywords meta tags.