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If the dictionary does not have it hyphenated and it does not substantially aid in avoiding confusion, leave it out.

If you're supposed to follow the Chicago Manual of Style, the relevant section is 5.91. Whether the adverb ends in -ly matters.

A phrasal adjective that comes before the noun it describes is generally hyphenated.
"The well-written essay received an A."

But there are exceptions. One such exception is that a two-word phrasal adjective that begins with an adverb ending in -ly is not hyphenated.
"The expertly written essay received an A."

And a phrasal adjective that comes after the noun it describes is usually unhyphenated.
"The essay that was well written received an A."
"The essay that was expertly written received an A."

Bryan A. Garner wrote:Do not hyphenate the phrase in these situations:

(1) When a phrase begins with an -ly adverb: newly admitted lawyer; legally permitted action; calmly spoken argument. An exception to this exception applies when the phrase is longer than two words. Hence: poorly-thought-out strategy.

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