What is first comment posting, and which APIs allow it

What is first comment posting?

The practice called first comment posting is publishing a comment on your own post right after it goes live, to hold hashtags or a link that would otherwise sit in the caption. The caption stays short and readable. The comment carries the tags. Scheduling tools automate it by firing a second API call as soon as the first one returns a post ID.

The idea only works where the platform treats a hashtag in a comment the same as one in the caption, and only where the API lets an app comment on the account's own content. Of the platforms covered here, only Instagram writes those rules down, in its Help Center.

Why do people put hashtags or links in the first comment?

To keep the caption clean while still tagging the post. Instagram's Help Center says so directly: "You can add hashtags in the caption or comments of your post. If you have a public account and add hashtags to a post, the post will be visible on the corresponding hashtag page."

The same page treats a comment as a way to tag a post after the fact: "If you want to add a hashtag to a post you've already uploaded, edit the caption or include your hashtag in a comment on your photo." That line is the closest thing to an official endorsement of the first comment habit. It puts caption and comment on equal footing for putting a post on a hashtag page.

Links are the other common use. People move a link into the first comment for the same layout reason. None of the platform documentation read for this page states that a link or a hashtag in a comment is ranked differently from one in the caption. If you have seen a claim about reach either way, it did not come from these docs.

Which APIs let you comment on your own post?

Instagram, Facebook and LinkedIn have a comment endpoint that an app can call on the account's own post. Threads, X and Bluesky have no separate comment object. On those three, the equivalent is a reply to your own post, created through the normal post endpoint.

Platform	Endpoint	Required fields	Access the docs list
Instagram	POST /<IG_MEDIA_ID>/comments	message	instagram_manage_comments (Facebook Login) or instagram_business_manage_comments (Instagram Login)
Facebook	POST /{object-id}/comments	One of message, attachment_id, attachment_share_url, attachment_url or source	pages_manage_engagement, plus a person who can perform the MODERATE task on the Page
LinkedIn	POST /rest/socialActions/{shareUrn|ugcPostUrn|commentUrn}/comments	actor, message, object	w_member_social_feed or w_organization_social_feed
Threads	POST /{threads-user-id}/threads with reply_to_id	media_type, reply_to_id	Threads user access token
X	POST /2/tweets with a reply object	text or media, reply	OAuth 2.0 user token
Bluesky	app.bsky.feed.post record with reply	text, createdAt, reply.root, reply.parent	The account's own session

Each row has its own details. Instagram's reference lists one limitation for creating comments: "Comments on live video IG Media are not supported." Facebook's comment edge returns the new comment's id and supports read-after-write. LinkedIn returns the comment ID in the x-restli-id response header and documents a throttle error, 429 "Comment create throttled: creation rate limit exceeded for member", described as "the short term 1 minute rate limit".

LinkedIn's two pages disagree about permissions. The Comments API page lists w_member_social_feed and w_organization_social_feed for writing comments. The Posts API page lists w_member_social and w_organization_social, each described as able to "Post, comment, and like posts". If a comment call fails with 403 while posting works, check which scope name your app actually holds. The layout and tagging rules for the post itself are in how to add hashtags to a LinkedIn post.

What do Instagram's docs say about hashtags in comments?

Two sources cover it, and they say different things. The developer docs cover how to post a comment. The Help Center covers what a hashtag in that comment does.

The Graph API reference for POST /<IG_MEDIA_ID>/comments says it "Creates an IG Comment on an IG Media object" and takes one required parameter, message, "The text to be included in the comment." It says nothing about hashtags. The Hashtag Search guide says the API finds "public IG Media that has been tagged with specific hashtags" and does not say whether a tag in a comment counts.

The Help Center fills the gap, and it contains the number most first comment setups get wrong. Under "Things to keep in mind" it says: "You can use up to 5 tags on a post. If you include more than 5 tags on a single photo/video, your comment won't post." A first comment with 20 hashtags does not get trimmed. It fails.

The same page leaves one question open. It does not say whether the 5 tags are counted across the caption and the comments together, or per piece of text. Until Instagram says, the safe reading is 5 per post in total. That means 3 tags in the caption and 3 more in the first comment is already one too many under that reading. Background on what a tag does and how hashtag pages collect posts is in what a hashtag is.

What is the timing trade-off?

The post is always live for a moment without its comment, because the comment endpoint needs the published post's ID and that ID only exists after publishing. On Instagram, POST /<IG_ID>/media_publish returns {"id": "<IG_MEDIA_ID>"}, and only then can POST /<IG_MEDIA_ID>/comments run.

For images the gap is the length of one API round trip. For video it can be longer, because the container has to finish processing before it can be published. Instagram's guide recommends "querying a container's status once per minute, for no more than 5 minutes." A tool that waits on that status and then comments will leave a video post live for as long as publishing took, plus one call.

The failure case is worse than the delay. If the comment call fails, whether from a LinkedIn 429, an Instagram comment with more than 5 tags, or a token that lacks the comment permission, the post stays up with no hashtags at all. Caption hashtags cannot fail separately from the post. First comment hashtags can.

Fixing a bad comment also takes more steps than fixing a caption on Instagram. The /<IG_MEDIA_ID>/comments reference says "Updating: This operation is not supported." To change the tags you delete the comment with DELETE /<IG_COMMENT_ID> and post a new one. LinkedIn is different: its Comments API lets you edit text and attributes in an existing comment's message.

Facebook scheduled posts raise one more question the docs do not answer. A post created with published=false and a scheduled_publish_time returns an ID right away, but neither the Posts guide nor the comments reference says whether commenting on it before it goes live is allowed. Queue the comment for after the publish time rather than relying on behaviour Meta has not documented. Comment handling after publication is covered in Facebook comment management.

Where the gap sits on Instagram

Container finishes processing

media_publish returns the media ID

Post is live without tags

Comment call runs

Tags appear, or the call fails and the post stays without them

Should you use the first comment or the caption?

Use the caption unless you have a specific reason for the comment. The caption publishes in the same call as the post, cannot fail separately, and on Instagram can be edited in place. The first comment buys a shorter caption, at the cost of a moment without tags, a second call that can fail, and a delete and repost to fix mistakes.

If you do use the first comment, build the tool around the failure case. Check the tag count against Instagram's 5 before publishing. Make the comment call retry on its own. Record whether it succeeded so someone sees a post that went out without its tags. The workflow around the post itself is the same one covered in how to schedule Instagram posts.

Frequently asked questions

Can you post a first comment on Instagram through the API?

Yes. Send POST /<IG_MEDIA_ID>/comments with a message parameter after media_publish returns the media ID. The access token needs instagram_manage_comments with Facebook Login or instagram_business_manage_comments with Instagram Login. Comments on live video media are not supported.

Do hashtags in the first comment work on Instagram?

Instagram's Help Center says "You can add hashtags in the caption or comments of your post", and that a public post with hashtags appears on the matching hashtag page. It does not describe any ranking difference between the two placements.

How many hashtags can an Instagram first comment hold?

Instagram's Help Center says "You can use up to 5 tags on a post" and "If you include more than 5 tags on a single photo/video, your comment won't post." It does not say whether caption and comment tags share that limit, so plan for 5 in total.

Can you edit a first comment through the Instagram API?

No. The /<IG_MEDIA_ID>/comments reference lists updating as "not supported". Delete the comment with DELETE /<IG_COMMENT_ID> and post a new one. LinkedIn's Comments API does allow editing the text of an existing comment.

Which permission does a Facebook Page need to comment on its own post?

Meta's /{object-id}/comments reference asks for "A Page access token requested by a person who can perform the MODERATE task on the Page" and the pages_manage_engagement permission. The request needs a message or one of the attachment fields.

Does first comment posting work on Threads and X?

Both use a reply to your own post instead of a comment. On Threads, create a new post with reply_to_id set to the original post's ID. On X, send POST /2/tweets with a reply object that points at the original post.

How long is a post live without its first comment?

For images, the gap is one API round trip, because the comment call runs as soon as media_publish returns the media ID. For video it can be longer, since the container has to finish processing before it can be published. Instagram's guide recommends querying a container's status once per minute, for no more than 5 minutes.

What happens if the first comment fails to post?

The post stays live with no hashtags. Causes include a LinkedIn 429 throttle, an Instagram comment with more than 5 tags, or a token that lacks the comment permission. Retry the call automatically and record whether it succeeded, so someone notices a post that went out without its tags.

Should hashtags go in the caption or the first comment?

Use the caption unless you have a specific reason for the comment. The caption publishes in the same call as the post, cannot fail separately, and on Instagram can be edited in place. The first comment buys a shorter caption, at the cost of a moment without tags and a second call that can fail.

Which LinkedIn scope does a first comment need?

LinkedIn's Comments API page lists w_member_social_feed and w_organization_social_feed for writing comments. The Posts API page lists w_member_social and w_organization_social, described as able to "Post, comment, and like posts". If a comment call returns 403 while posting works, check which scope name your app actually holds.