Skip to main content
The GitHub Create a review comment for a pull request action adds targeted, line-level review comments to an existing pull request. Use this write action to leave code review feedback directly on the diff, for example when flagging documentation or style issues in changed files. Specify the exact location for the comment using commit ID, file path, and diff position details. The action does not create pull requests or submit overall approvals or change requests.

​
Limitations

  • Requires a valid combination of owner, repo, pull_number, commit_id, path, and location fields like line or position, and optional start_line/start_side that map to a real line in the pull request diff. Invalid locations will cause the action to fail.
  • Like other GitHub actions, calls are subject to GitHub API rate limits. Heavy automation or tight loops can cause intermittent failures until rate limits reset.

​
Prerequisites

  • Your admin must install and configure the GitHub connector, add the GitHub actions pack under Admin > Actions, and enable this action. For more information see GitHub actions setup.
  • A GitHub app must be installed on the relevant organization(s) and linked to the correct GitHub datasource in the Glean admin console.
  • You must authenticate for GitHub actions so the action can run using your GitHub identity. Your identity must have permission to view the diff and post review comments in the target repository.

​
Parameters

ParameterTypeDescription
Comment bodyStringText content of the review comment.
Commit IDStringThe commit SHA that the comment should be associated with.
OwnerStringOwner of the repository that contains the pull request.
File pathStringFile path in the repository where you want to add the comment.
Pull request numberIntegerNumber of the pull request to comment on.
RepositoryStringName of the repository that contains the pull request.
Reply to commentIntegerID of an existing review comment if you want to reply in an existing review thread instead of creating a new one.
Line numberIntegerLine number in the file where the comment should appear (for unified diff mode). Use either line or position depending on how your agent computes locations.
PositionIntegerPosition in the diff where the comment should appear (for diff-based positioning). Use either line or position.
SideStringSide of the diff to comment on, for example the original or the modified side of the change.
Start lineIntegerStarting line number for a multi-line comment range.
Start sideStringSide of the diff for the starting line of a multi-line comment range.
Subject typeStringType of subject the comment applies to, for example a line or file-level comment, depending on how the underlying API is configured.

​
Usage example

You are reviewing a pull request and notice a function is missing documentation. You want to leave a comment on that specific line suggesting the author add documentation. Instruction to an agent: “Add a review comment to pull request #127 in mycompany/backend repository at line 45 in the file src/api/users.py, suggesting that the function needs documentation.” Resulting behavior:
  • Calls Get a pull request to retrieve details for PR #127 including the latest commit SHA.
  • Calls Create a review comment for a pull request with:
    • Owner set to “mycompany”.
    • Repository set to “backend”.
    • Pull request number set to 127.
    • Commit ID set to the latest commit SHA (for example, “abc123def456”).
    • File path set to “src/api/users.py”.
    • Line number set to 45.
    • Side set to “RIGHT” to comment on the modified version.
    • Comment body set to “Please add documentation for this function explaining the parameters, return value, and any exceptions it may raise.”
  • Creates a review comment on the pull request at the specified line.
  • The comment appears in the pull request diff view attached to line 45 of the file.
  • The pull request author receives a notification about the new comment.
Workflow tip: Use this action with Get a pull request to first retrieve the latest commit SHA. For multi-line comments, use Start line and Start side parameters. Combine with other GitHub actions like requesting reviewers or listing commits to build comprehensive code review agents.

​
Troubleshooting

  • Possible cause: The owner, repository, or pull_number values do not match an existing pull request that is available through your GitHub connector, or the authenticated identity cannot access that pull request.
  • Fix: Confirm that the repository is connected in Glean, the pull request exists in GitHub, and the identifiers you passed match the pull request.
  • Possible cause: Hitting GitHub API rate limits.
  • Fix: Reduce how frequently the action is called, add delays between calls, or batch comments where possible. If this keeps happening, contact your Glean admin to review configuration and usage.
  • Possible cause: GitHub actions are not enabled for your organization, the datasource instance is not configured for actions, or your GitHub identity does not have permission to comment on pull requests in the target repository.
  • Fix: Ask your Glean admin to confirm that the relevant GitHub datasource instance is added with actions enabled and that you are allowed to use this action.

​
FAQs

No. This action creates individual review comments. To submit a full review (approve or request changes), use the separate GitHub actions that create or submit a review for a pull request, and combine them with this action if you need both behaviors.
No. You must provide enough location information such as commit_id, path, and either line or position for GitHub to attach the comment to a specific place in the pull request diff.