short and sweet

short and sweet (without unnecesary details, concise) — коротко и ясно; без излишних подробностей;
≅ не растекаться мыслею по древу

Example 1: A long letter of complaint would be annoying, so when you write it, try to make it short and sweet.

Example 2: If you want your letter to be published in the newspaper, keep it short and sweet.