---
title: Review GitLab Merge Requests
description: "Complete workflow for AI-powered merge request reviews with GitLab MCP. Find MRs to review, view diffs, read discussions, leave feedback, and approve changes with step-by-step prompts."
head:
- - meta
- name: keywords
content: gitlab code review, merge request review, ai code review, mr diff, approve merge request, review workflow
---
# Review GitLab Merge Requests
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`"
::: code-group
```json [Awaiting my review]
{
"action": "list",
"project_id": "my-org/api",
"state": "opened",
"reviewer_username": "my-username",
"per_page": 20
}
```
```json [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?"
::: code-group
```json [MR details]
{
"action": "get",
"project_id": "my-org/api",
"merge_request_iid": "42"
}
```
```json [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?"
::: code-group
```json [Full diff]
{
"action": "diffs",
"project_id": "my-org/api",
"merge_request_iid": "42",
"per_page": 50
}
```
```json [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?"
```json [List 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"
::: code-group
```json [General comment]
{
"action": "comment",
"project_id": "my-org/api",
"noteable_type": "merge_request",
"noteable_id": "42",
"body": "LGTM! Clean implementation with good test coverage."
}
```
```json [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"
::: code-group
```json [Approve]
{
"action": "approve",
"project_id": "my-org/api",
"merge_request_iid": "42"
}
```
```json [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](/prompts/code-review/suggest-changes) — Add code suggestions
- [Apply Feedback](/prompts/code-review/apply-feedback) — Apply suggestions from reviews
