AI agents use unapprove_merge_request to create or update resources in Gitlab — usually the action step of a workflow, after the agent has gathered context. Every call changes real data in your Gitlab environment.
This tool modifies metadata (approval status) on an existing merge request. It is reversible (the user can re-approve), so it falls under Write rather than Destructive. The blast radius is medium because an agent that unapproves critical merge requests could delay or gate releases, but the action can be undone. It does not execute arbitrary code (Execute), delete data (Destructive), or move money (Financial).
From the tool's definition Tool performs 'Remove your approval from a merge request' — this is a state modification operation that changes the approval status of a merge request, reversing a prior action without deleting underlying data.
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, 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.
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Remove your approval from a merge request. It is categorised as a Write tool in the Gitlab MCP Server, which means it can create or modify data. Consider rate limits to prevent runaway writes.
Register the Gitlab 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. 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 server (yoda-digital/mcp-gitlab-server). PolicyLayer sits as a proxy in front of this server to enforce policies before tool calls reach the server.
Deterministic rules across all 88 Gitlab tools. Per-identity grants. Full audit log. Live in minutes. Nothing to install.
Free to start. No card required.
88 Gitlab tools catalogued and risk-classified — across an index of 42,500+ MCP servers.