The description you provide for your API parameters show up in documentation, tooltips, intellisense, and other layers of the API lifecycle. Parameter descriptions should really be a single paragraph, maybe two at the most, and share a narrative that will make sense to consumers.
Keep examples and other technical details out of the description and utilize other OpenAPI properties, keeping your descriptions easy to read and speaking to how to configure the API request. Make sure to print out the names and descriptions of all your API parameters in a single bulleted list, read them out loud, and make sure they all make sense to you.