create_merge_request · GitLab Review MCP: Risk & Policy

WHAT IT DOES

What create_merge_request does on GitLab Review MCP

AI agents use create_merge_request to create or update resources in GitLab Review MCP — usually the action step of a workflow, after the agent has gathered context. Every call changes real data in your GitLab Review MCP environment.

WHY IT NEEDS A POLICY

Why create_merge_request needs a policy

Creating a merge request is a reversible write operation—it creates a code review artifact that can be closed or deleted, but it commits code changes to the repository and triggers CI/CD pipelines and reviewer notifications. This is Write rather than Execute because the tool itself doesn't run arbitrary code; it invokes a defined GitLab operation.

From the tool's definition Tool name is 'create_merge_request' and description states 'Create a new GitLab merge request from a source branch'. This directly creates new data (a merge request) in the repository.

Attacks that exploit this kind of access

Recommended rule Ready

Verdict

create_merge_request Rate-limited

create_merge_request stays usable, but capped — an agent stuck in a loop can't make hundreds of changes a minute. Everything else on the server is denied unless you say otherwise.

View as policy code

policy.json

{
  "version": "1",
  "default": "deny",
  "tools": {
    "create_merge_request": {
      "limits": [
        {
          "counter": "create_merge_request_rate",
          "window": "minute",
          "max": 30,
          "scope": "grant"
        }
      ]
    }
  }
}

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Instant setup, no code required.

PolicyLayer is an MCP gateway: every tool call is checked against your rule before it reaches GitLab Review MCP, so you can run agents against it safely.

FAQ

Questions about create_merge_request

What does the create_merge_request tool do? +

Create a new GitLab merge request from a source branch. It is categorised as a Write tool in the GitLab Review MCP MCP Server, which means it can create or modify data. Consider rate limits to prevent runaway writes.

How do I enforce a policy on create_merge_request? +

Register the GitLab Review MCP server in PolicyLayer and add a rule for create_merge_request: allow, deny, rate-limit, or require approval. Point your MCP client at the PolicyLayer proxy URL and the rule is enforced on every call, before it reaches GitLab Review MCP. Nothing to install.

What risk level is create_merge_request? +

create_merge_request is a Write tool with medium risk. Write tools should be rate-limited to prevent accidental bulk modifications.

Can I rate-limit create_merge_request? +

Yes. Add a rate_limit block to the create_merge_request rule in your PolicyLayer policy. For example, setting max: 10 and window: 60 limits the tool to 10 calls per minute. Rate limits are tracked per agent session and reset automatically.

How do I block create_merge_request completely? +

Set action: deny in the PolicyLayer policy for create_merge_request. The AI agent will receive a policy violation error and cannot call the tool. You can also include a reason field to explain why the tool is blocked.

What MCP server provides create_merge_request? +

create_merge_request is provided by the GitLab Review MCP server (lininn/gitlab-review-mcp). PolicyLayer sits as a proxy in front of this server to enforce policies before tool calls reach the server.