unapprove_merge_request · GitLab Code Review MCP

WHAT IT DOES

What unapprove_merge_request does on GitLab Code Review MCP

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

WHY IT NEEDS A POLICY

Why unapprove_merge_request needs a policy

This tool modifies approval state on a merge request, which is a reversible write operation. While it doesn't delete data, it changes the approval status—a critical workflow state in code review processes. An AI agent misusing this could inappropriately retract approvals, disrupting the merge request workflow and potentially allowing unapproved code to merge.

From the tool's definition Tool name 'unapprove_merge_request' and description 'Unapprove a merge request' indicate a state-modification action on merge request approvals. This reverses a prior approval decision.

Attacks that exploit this kind of access

Recommended rule Ready

Verdict

unapprove_merge_request Rate-limited

unapprove_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": {
    "unapprove_merge_request": {
      "limits": [
        {
          "counter": "unapprove_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 Code Review MCP, so you can run agents against it safely.

FAQ

Questions about unapprove_merge_request

What does the unapprove_merge_request tool do? +

Unapprove a merge request. It is categorised as a Write tool in the GitLab Code 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 unapprove_merge_request? +

Register the GitLab Code Review MCP server in PolicyLayer and add a rule for unapprove_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 Code Review MCP. Nothing to install.

What risk level is unapprove_merge_request? +

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

Can I rate-limit unapprove_merge_request? +

Yes. Add a rate_limit block to the unapprove_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 unapprove_merge_request completely? +

Set action: deny in the PolicyLayer policy for unapprove_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 unapprove_merge_request? +

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