AI agents use gitlab_merge_rules to create or update resources in Gitlab Api — usually the action step of a workflow, after the agent has gathered context. Every call changes real data in your Gitlab Api environment.
Based on the tool name and GitLab API context, this tool most likely creates or modifies merge request rules (e.g., approval requirements, protected branch settings). Such changes are reversible (Write category) rather than destructive, but carry high severity because misconfigured merge rules could bypass security controls, affect code review processes, or allow unauthorized code merging.
From the tool's definition Tool name 'gitlab_merge_rules' combined with GitLab API context suggests modification of merge request rules/policies. No description provided, but 'merge_rules' in GitLab typically involves creating or updating branch protection and approval policies.
Documented attack patterns abuse exactly the kind of access gitlab_merge_rules gives an agent:
PolicyLayer is an MCP gateway — it sits between your AI agents and Gitlab Api, and nothing reaches the server without passing your rules. This is the rule we recommend for gitlab_merge_rules:
{
"version": "1",
"default": "deny",
"tools": {
"gitlab_merge_rules": {
"limits": [
{
"counter": "gitlab_merge_rules_rate",
"window": "minute",
"max": 30,
"scope": "grant"
}
]
}
}
}gitlab_merge_rules 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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gitlab_merge_rules. It is categorised as a Write tool in the Gitlab Api MCP Server, which means it can create or modify data. Consider rate limits to prevent runaway writes.
Register the Gitlab Api MCP server in PolicyLayer and add a rule for gitlab_merge_rules: 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 Api. Nothing to install.
gitlab_merge_rules 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 gitlab_merge_rules 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 gitlab_merge_rules. 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.
gitlab_merge_rules is provided by the Gitlab Api MCP server (knuckles-team/gitlab-api). PolicyLayer sits as a proxy in front of this server to enforce policies before tool calls reach the server.
Start from Gitlab Api, add the rest of your stack, and see everything your agents can call. Then put policy on all of it.
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26 Gitlab Api tools catalogued and risk-classified — across an index of 43,000+ MCP servers.