AI agents use unapprove_merge_request to create or update resources in GitLab MCP for Code Review — usually the action step of a workflow, after the agent has gathered context. Every call changes real data in your GitLab MCP for Code Review environment.
This tool modifies data (approval status) but does not delete or destroy information. It is reversible (can be re-approved), placing it in the Write category rather than Destructive. The severity is medium because unapproving a merge request could interfere with CI/CD workflows and code release processes, but the action is not irreversible and does not involve financial or execute-level risk.
From the tool's definition Tool performs 'unapprove a merge request'—a reversible state change that modifies the approval status of a merge request in GitLab, similar to the 'approve_merge_request' sibling tool.
Documented attack patterns abuse exactly the kind of access unapprove_merge_request gives an agent:
PolicyLayer is an MCP gateway — it sits between your AI agents and GitLab MCP for Code Review, and nothing reaches the server without passing your rules. This is the rule we recommend for unapprove_merge_request:
{
"version": "1",
"default": "deny",
"tools": {
"unapprove_merge_request": {
"limits": [
{
"counter": "unapprove_merge_request_rate",
"window": "minute",
"max": 30,
"scope": "grant"
}
]
}
}
}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.
Free to start. No card required.
Unapprove a merge request. It is categorised as a Write tool in the GitLab MCP for Code Review MCP Server, which means it can create or modify data. Consider rate limits to prevent runaway writes.
Register the GitLab MCP for 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 MCP for Code Review. Nothing to install.
unapprove_merge_request is a Write tool with medium risk. Write tools should be rate-limited to prevent accidental bulk modifications.
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.
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.
unapprove_merge_request is provided by the GitLab MCP for Code Review MCP server (mehmetakinn/gitlab-mcp-code-review). PolicyLayer sits as a proxy in front of this server to enforce policies before tool calls reach the server.
Start from GitLab MCP for Code Review, add the rest of your stack, and see everything your agents can call. Then put policy on all of it.
Free to start. No card required.
8 GitLab MCP for Code Review tools catalogued and risk-classified — across an index of 43,000+ MCP servers.