Add Review Comment Skill

Add Review Comment

Posts one inline review comment to a specific line in a GitHub pull request using the GitHub REST API via the gh CLI.

This is a pure worker skill: one invocation posts exactly one comment. Give it the anchor (path, line, optional range and side) and the comment body; it resolves the head commit, posts the comment, and returns the new comment's html_url. It does not decide what to review or batch multiple findings — a caller (such as pr-review) drives that and calls this once per finding.

When to Use

You have a single finding and want to anchor a comment to the exact line.
You need a multi-line comment spanning a range of changed lines.
You want to attach a one-click suggestion block to a PR line.

For reviewing a whole PR and emitting a full set of comments, use the pr-review skill instead.

Step 1: Locate the line to comment on

Invoke the fetch-diff skill to fetch the PR diff with line numbers, then identify the path, line, and side to anchor to:

side=RIGHT — added or context lines (the post-merge file). The common case.
side=LEFT — deleted lines (the pre-change file).

Step 2: Post the comment

Single-line comment — the body must end with the 🤖 Generated with Claude footer on its own line:

gh api repos/<owner>/<repo>/pulls/<pr_number>/comments \
  -f body=<comment> \
  -f path=<file_path> \
  -F line=<line_number> \
  -f side=<side> \
  -f commit_id="$(gh pr view <pr_number> --repo <owner>/<repo> --json headRefOid -q .headRefOid)" \
  --jq '.html_url'

Multi-line comment — anchors a range from start_line to line:

gh api repos/<owner>/<repo>/pulls/<pr_number>/comments \
  -f body=<comment> \
  -f path=<file_path> \
  -F start_line=<first_line> \
  -f start_side=<side> \
  -F line=<last_line> \
  -f side=<side> \
  -f commit_id="$(gh pr view <pr_number> --repo <owner>/<repo> --json headRefOid -q .headRefOid)" \
  --jq '.html_url'

Parameters

| Parameter | Meaning | |-----------|---------| | path | File path relative to the repo root; must have a hunk in the PR diff | | line | Anchor line (for multi-line comments, the last line of the range) | | side | RIGHT for added/modified lines, LEFT for deleted lines | | start_line / start_side | First line of the range (multi-line comments only) | | commit_id | Head commit SHA — resolved inline via gh pr view above |

Best Practices

Use suggestion blocks for simple fixes maintainers can apply in one click — fence with triple backticks and the word suggestion, and preserve the original indentation exactly:
```
```suggestion
<suggested code here>
```
```
For a repeated issue, leave one representative comment rather than flagging every instance.
For bugs, state the problem, why it matters, and a concrete fix.
Always end the comment body with 🤖 Generated with Claude on its own line.

Output

A successful post returns the new comment's html_url (a permalink to the inline comment) — that single URL is what the caller gets back and can surface or log. A failed post returns a non-zero exit and an HTTP error from gh api (typically 401 for auth or 422 for a bad line anchor); see the troubleshooting reference for how to read each one.

Reference Files

references/api-reference.md — consult when constructing the request: the gh api endpoint, the full parameter table, single-line vs multi-line anchor rules, side selection, and suggestion block syntax.
references/troubleshooting.md — consult when a post fails: auth errors and the line-anchor pitfalls behind 422 responses (line not in the diff, wrong side, stale commit_id, inverted start_line).

Related skills

This skill is the "post one comment" worker in the PR-review family. A typical flow chains them:

fetch-diff — fetch the PR diff with real file line numbers, so you know which path/line/side to anchor to.
add-review-comment (this skill) — post a single inline comment to one of those lines.
pr-review — review a whole PR and drive this skill once per finding.
fetch-unresolved-comments — read the open review threads on a PR, e.g. to follow up on comments left here.

Agent Skills: Add Review Comment

Install this agent skill to your local

Skill Files