AI agents use merge_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 creates a permanent change to the codebase by merging code changes, which is a write operation that modifies the repository. While the change is technically reversible (via revert or new commits), the immediate effect is to irreversibly integrate changes into the target branch.
From the tool's definition Tool name 'merge_merge_request' and description 'Merge a merge request' indicate modification of code repository state by integrating proposed changes into a target branch.
Documented attack patterns abuse exactly the kind of access merge_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 merge_merge_request:
{
"version": "1",
"default": "deny",
"tools": {
"merge_merge_request": {
"limits": [
{
"counter": "merge_merge_request_rate",
"window": "minute",
"max": 30,
"scope": "grant"
}
]
}
}
}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.
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Merge 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 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. Nothing to install.
merge_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 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.
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.
merge_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.
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88 Gitlab tools catalogued and risk-classified — across an index of 42,500+ MCP servers.