merge_merge_request · GitLab MCP: Risk & Policy

WHAT IT DOES

What merge_merge_request does on GitLab MCP

AI agents use merge_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 merge_merge_request needs a policy

Merging a merge request commits code to a target branch, modifying the repository state. While significant, this is a standard write operation that can be undone via revert commits. High severity because unintended merges could introduce bugs, security issues, or break production code, but not critical since reversions are possible.

From the tool's definition Tool name 'merge_merge_request' with description 'Accept (merge) a merge request' indicates it modifies repository state by integrating code changes. The action is reversible through GitLab's revert functionality, placing it in Write rather than Destructive.

Attacks that exploit this kind of access

Recommended rule Ready

Verdict

merge_merge_request Rate-limited

merge_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": {
    "merge_merge_request": {
      "limits": [
        {
          "counter": "merge_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 merge_merge_request

What does the merge_merge_request tool do? +

Accept (merge) a merge request. 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 merge_merge_request? +

Register the GitLab MCP server in PolicyLayer and add a rule for merge_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 merge_merge_request? +

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

Can I rate-limit merge_merge_request? +

Yes. Add a rate_limit block to the merge_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 merge_merge_request completely? +

Set action: deny in the PolicyLayer policy for merge_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 merge_merge_request? +

merge_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.