syouhinsetumei ni, zyoutai dake de naku dousakakunin mo iremasu.

Here, 商品説明に means in the product description.

The verb 入れる literally means to put in, so Japanese treats 商品説明 as the place/container something is being put into.

• 商品説明に入れる = put/include it in the product description

So に marks the destination or container.

A rough structure is:

• A に B を入れる = put B into A

In this sentence, the things being put into the description are 状態 and 動作確認.

だけでなく ～ も means not only ..., but also ...

In this sentence:

• 状態だけでなく動作確認も
• not only the condition/status, but also the operation check

This is a very common pattern.

Examples:

• 日本語だけでなく、中国語も話せます。
  = I can speak not only Japanese, but also Chinese.

• 値段だけでなく、品質も大切です。
  = Not only price, but also quality is important.

So the core pattern is:

• X だけでなく Y も

The も is part of the pattern XだけでなくYも.

It highlights the second item as also being included.

So:

• 状態だけでなく動作確認も入れます
• I’ll include not only the condition, but also the operation check

Also, も often replaces other particles such as を, が, or は.

Here, the thing being included would normally be marked like an object, but も takes that spot.

So you do not normally say:

• 動作確認をも入れます

Instead, natural Japanese is:

• 動作確認も入れます

This is normal in the pattern XだけでなくYも.

When two nouns are contrasted this way, the first noun often appears without its usual particle:

• 状態だけでなく動作確認も

This does not mean the grammar is broken. It is just how this structure commonly works.

Compare:

• コーヒーだけでなく、お茶も飲みます。
  = I drink not only coffee, but also tea.

You do not need a particle after コーヒー there either.

So 状態 and 動作確認 are being presented as parallel items:

• not only condition
• but also operation check

動作確認 literally means operation check or checking that it works.

In the context of selling an item, it usually means something like:

• tested and confirmed that it operates
• functionality check
• working condition confirmation

So in a product listing, 状態 is about the item’s physical condition, while 動作確認 is about whether it actually works.

For example:

• 状態 = scratches, wear, appearance
• 動作確認 = whether the device powers on or functions properly

入れます literally means put in, but in this kind of sentence it often means include, add, or put into the description.

So this sentence is not about physically putting something into a box. It means adding information to the written product description.

Natural English equivalents would be:

• I’ll include ... in the product description
• I’ll add ... to the product description

So 入れる is being used figuratively here.

It can be either, depending on context.

Japanese non-past forms like 入れます can mean:

• I include
• I will include
• I’m going to include

In this sentence, the most natural reading is probably future or intended action:

• I’ll include not only the condition but also the operation check in the product description.

But if the speaker is talking about their usual practice, it could also mean:

• I include not only the condition but also the operation check in the product description.

Japanese often leaves that distinction to context.

Yes, that is a very natural interpretation here.

状態 is a broad word meaning state, condition, or status.
In a product description, it usually refers to the item’s condition, such as:

• appearance
• damage
• cleanliness
• signs of use

So in this context, condition is a very good English equivalent.

Yes, and the nuance would change slightly.

• 入れます = put in / include / add
  More conversational and straightforward.

• 載せます = put on / post / include in a listing
  Often used for information shown in print or online.

• 記載します = state / mention in writing
  More formal and business-like.

So:

• 商品説明に、状態だけでなく動作確認も入れます。
  sounds like I’ll add that information to the product description.

A more formal version could be:

• 商品説明に、状態だけでなく動作確認も記載します。

The comma is mainly for readability.

It separates:

• 商品説明に = in the product description from
• 状態だけでなく動作確認も入れます = the main content being included

Japanese commas are often flexible. The sentence would still be understandable without it:

• 商品説明に状態だけでなく動作確認も入れます。

With the comma, it is just a little easier to read.

Yes, it is natural and understandable.

It sounds like something someone would say when talking about what they will write in a product listing or item description.

The tone is polite because of 入れます.

A slightly more formal or listing-style version might be:

• 商品説明に、状態だけでなく動作確認についても記載します。

But the original sentence is perfectly natural in everyday use.