add_pr_comment · Code Review MCP: Risk & Policy

WHAT IT DOES

What add_pr_comment does on Code Review

AI agents use add_pr_comment to create or update resources in Code Review — usually the action step of a workflow, after the agent has gathered context. Every call changes real data in your Code Review environment.

WHY IT NEEDS A POLICY

Why add_pr_comment needs a policy

This tool creates new comments on PRs/MRs, modifying the review record reversibly. It is not destructive (comments can be deleted), does not execute arbitrary code or shell commands, and does not move money. The severity is medium because a malicious agent could spam, harass, or mislead developers with false review feedback, but the blast radius is limited to PR discussions and the action is reversible.

From the tool's definition Tool description states 'Add a general comment to PR/MR' — explicitly a create operation that adds new data to a pull request or merge request.

Attacks that exploit this kind of access

Recommended rule Ready

Verdict

add_pr_comment Rate-limited

add_pr_comment 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.

View as policy code

policy.json

{
  "version": "1",
  "default": "deny",
  "tools": {
    "add_pr_comment": {
      "limits": [
        {
          "counter": "add_pr_comment_rate",
          "window": "minute",
          "max": 30,
          "scope": "grant"
        }
      ]
    }
  }
}

LIMIT THIS TOOL →

Instant setup, no code required.

PolicyLayer is an MCP gateway: every tool call is checked against your rule before it reaches Code Review, so you can run agents against it safely.

FAQ

Questions about add_pr_comment

What does the add_pr_comment tool do? +

Add a general comment to PR/MR. It is categorised as a Write tool in the Code Review MCP Server, which means it can create or modify data. Consider rate limits to prevent runaway writes.

How do I enforce a policy on add_pr_comment? +

Register the Code Review MCP server in PolicyLayer and add a rule for add_pr_comment: 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 Code Review. Nothing to install.

What risk level is add_pr_comment? +

add_pr_comment is a Write tool with medium risk. Write tools should be rate-limited to prevent accidental bulk modifications.

Can I rate-limit add_pr_comment? +

Yes. Add a rate_limit block to the add_pr_comment 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.

How do I block add_pr_comment completely? +

Set action: deny in the PolicyLayer policy for add_pr_comment. 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.

What MCP server provides add_pr_comment? +

add_pr_comment is provided by the Code Review MCP server (oldjii/code-review-mcp). PolicyLayer sits as a proxy in front of this server to enforce policies before tool calls reach the server.