Review a Merge Request

Complete workflow for performing a thorough code review using GitLab MCP.

Step 1: Find MRs to Review

"Show me MRs waiting for my review in my-org/api"

"List open MRs with label needs-review in my-org/frontend"

Awaiting my review

{
  "action": "list",
  "project_id": "my-org/api",
  "state": "opened",
  "reviewer_username": "my-username",
  "per_page": 20
}

By label

{
  "action": "list",
  "project_id": "my-org/api",
  "state": "opened",
  "labels": "needs-review",
  "per_page": 20
}

Step 2: Get MR Details

"Show me the details of MR !42 in my-org/api"

"What's the description and discussion status of MR !42?"

MR details

{
  "action": "get",
  "project_id": "my-org/api",
  "merge_request_iid": "42"
}

MR by branch

{
  "action": "get",
  "project_id": "my-org/api",
  "branch_name": "feature/login-refactor"
}

Step 3: View the Diff

"Show me the file changes in MR !42"

"What files were modified in this MR?"

Full diff

{
  "action": "diffs",
  "project_id": "my-org/api",
  "merge_request_iid": "42",
  "per_page": 50
}

Compare branches

{
  "action": "compare",
  "project_id": "my-org/api",
  "from": "main",
  "to": "feature/login-refactor"
}

Step 4: Read Existing Discussions

"Show me the discussion threads on MR !42"

"Are there unresolved discussions?"

{
  "action": "list",
  "project_id": "my-org/api",
  "merge_request_iid": "42",
  "per_page": 50
}

Step 5: Leave Feedback

"Add a comment on MR !42 saying the implementation looks good"

"Start a discussion thread on MR !42 about the error handling"

General comment

{
  "action": "comment",
  "project_id": "my-org/api",
  "noteable_type": "merge_request",
  "noteable_id": "42",
  "body": "LGTM! Clean implementation with good test coverage."
}

Start a thread

{
  "action": "thread",
  "project_id": "my-org/api",
  "merge_request_iid": "42",
  "body": "Consider adding error handling for the null case here."
}

Step 6: Approve or Request Changes

"Approve MR !42 in my-org/api"

"Check the approval status of MR !42"

Approve

{
  "action": "approve",
  "project_id": "my-org/api",
  "merge_request_iid": "42"
}

Check approval state

{
  "action": "get_approval_state",
  "project_id": "my-org/api",
  "merge_request_iid": "42"
}

Tips for Effective Reviews

1. Read the description first — Understand the intent before looking at code
2. Check the diff size — Large diffs may need multiple review passes
3. Look at test coverage — Verify tests exist for new functionality
4. Check pipeline status — Ensure CI passes before approving
5. Use suggestions — Provide concrete fixes, not just complaints

Next Steps

• Suggest Changes — Add code suggestions
• Apply Feedback — Apply suggestions from reviews