create_merge_request · GitLab MCP: Risk & Policy

WHAT IT DOES

What create_merge_request does on GitLab MCP

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

WHY IT NEEDS A POLICY

Why create_merge_request needs a policy

Creating a merge request is a Write operation—it creates a new reversible artifact in the repository's code review workflow. While it proposes code changes, the merge request itself is not immediately deployed and can be discarded, closed, or superseded.

From the tool's definition Tool description states 'Open a merge request', and the sibling tools include `approve_merge_request`, `cancel_pipeline`, `comment_issue`, and `create_commit`, indicating this server manages reversible code review and collaboration workflows.

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 MCP, so you can run agents against it safely.

FAQ

Questions about create_merge_request

What does the create_merge_request tool do? +

Open a merge request from source_branch into target_branch. It is categorised as a Write tool in the GitLab 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 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 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 MCP server (shahabmosavi/gitlab_mcp). PolicyLayer sits as a proxy in front of this server to enforce policies before tool calls reach the server.