Add note to existing MR discussion thread.
How to control gitlab_create_merge_request_discussion_note ↓
AI agents use gitlab_create_merge_request_discussion_note 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 new content (a discussion note) on a merge request, which is a Write operation. It modifies GitLab state but is reversible (notes can be deleted). Severity is medium because while it could be misused to spam discussions or inject misleading comments into code review, the impact is localized to communication and reversible.
From the tool's definition Tool description states 'Add note to existing MR discussion thread' — the word 'Add' indicates creation of new data (a note/comment). The tool modifies the state of a merge request by appending a discussion note, which is reversible through deletion.
Documented attack patterns abuse exactly the kind of access gitlab_create_merge_request_discussion_note 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 gitlab_create_merge_request_discussion_note:
{
"version": "1",
"default": "deny",
"tools": {
"gitlab_create_merge_request_discussion_note": {
"limits": [
{
"counter": "gitlab_create_merge_request_discussion_note_rate",
"window": "minute",
"max": 30,
"scope": "grant"
}
]
}
}
}gitlab_create_merge_request_discussion_note 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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Add note to existing MR discussion thread. 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 gitlab_create_merge_request_discussion_note: 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.
gitlab_create_merge_request_discussion_note 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_create_merge_request_discussion_note 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_create_merge_request_discussion_note. 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_create_merge_request_discussion_note is provided by the Gitlab MCP server (mcpland/gitlab-mcp). PolicyLayer sits as a proxy in front of this server to enforce policies before tool calls reach the server.
Start from Gitlab, 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.
190 Gitlab tools catalogued and risk-classified — across an index of 43,000+ MCP servers.