Support standalone inline PR review comments #3485

Describe the feature or problem you'd like to solve

GitHub's UI allows posting an inline PR comment using "Add single comment", without starting or submitting a pull request review.

With github-mcp-server, the currently supported workflow for inline comments appears to be review-oriented:

1. Create a pending review
2. Add comments using add_comment_to_pending_review
3. Submit the review

This makes sense when an agent is performing a complete code review, but not every inline observation necessarily represents a review.

For example, an agent may simply want to leave a comment such as:

Consider extracting this into a separate method.

on a specific line and continue its workflow.

Currently, doing this requires creating and subsequently submitting a review, which introduces additional state and has different semantics from GitHub's native "Add single comment" functionality.

Proposed solution

Expose a tool for creating a standalone inline pull request review comment, for example:

create_pull_request_review_comment

The tool could map to GitHub's existing REST API:

POST /repos/{owner}/{repo}/pulls/{pull_number}/comments

and accept the corresponding parameters such as:

• repository
• pull request number
• comment body
• commit SHA
• file path
• line / side
• optional start line / start side for multi-line comments

This would allow both workflows:

• Standalone inline comment — equivalent to GitHub's "Add single comment"
• Pending review comments — comments intentionally grouped into a review

Example prompts or workflows (for tools/toolsets only)

An agent inspecting a PR notices one localized issue and wants to comment directly on the relevant line:

This timeout is hard-coded. Should this use the configured request timeout instead?

The desired behavior would be to publish that comment immediately on the relevant line, without creating a pending review or requiring a subsequent review submission.

Additional context

I noticed that github-mcp-server explicitly supports and encourages the pending-review workflow, so the absence of standalone inline comments may be an intentional design decision.

If so, it would be useful to understand whether there is a technical, security, or agent-workflow reason for not exposing GitHub's standalone inline-comment API.

This request is not intended to change or replace add_comment_to_pending_review. It is about exposing the separate GitHub capability for cases where an agent wants to publish an individual inline comment without creating a review.