DocumentDB SQL with ARRAY_CONTAINS

I'm playing around on https://www.documentdb.com/sql/demo, which allows me to query against sample documents that look like:

{
  "id": "19015",
  "description": "Snacks, granola bars, hard, plain",
  "tags": [
    {
      "name": "snacks"
    }
  ],
  "version": 1,
  "isFromSurvey": false,
  "foodGroup": "Snacks",
  "servings": [
    {
      "amount": 1,
      "description": "bar",
      "weightInGrams": 21
    }
  ]
}

I'm confused about ARRAY_CONTAINS(). This query returns results:

SELECT root
FROM root 
WHERE ARRAY_CONTAINS(root.tags, { "name": "snacks" })

However, this query does not:

SELECT root
FROM root 
WHERE ARRAY_CONTAINS(root.servings, { "description": "bar" })

What gives?

What I'm trying to achieve is illustrated by how I would write the query if this was C#:

var filteredDocs = docs.Where(d => d.Servings != null &&
                                   d.Servings.Length > 0 &&
                                   d.Servings.Any(s => s.Description == "bar"));

It appears the first example query on root.tags works because { "name": "snacks" } is the entire object in the root.tags array, while, in the second query, { "description": "bar" } is only one field in the root.servings objects.

How can I modify the second query on root.servings to work with only knowing the serving description?