set_motd · OPanel MCP: Risk & Policy

WHAT IT DOES

What set_motd does on OPanel MCP

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

WHY IT NEEDS A POLICY

Why set_motd needs a policy

This tool creates or modifies server metadata (MOTD) reversibly with no side effects on game data, player data, or server operations. Changes to MOTD can be easily overwritten or reverted. While it affects server presentation, the blast radius is minimal—worst case is a confusing or offensive message to joining players, not data loss or financial impact.

From the tool's definition Tool description states 'Set the Message of the Day (MOTD) of the Minecraft server' — a clear write operation that modifies server configuration.

Attacks that exploit this kind of access

Recommended rule Ready

Verdict

set_motd Rate-limited

set_motd 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": {
    "set_motd": {
      "limits": [
        {
          "counter": "set_motd_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 OPanel MCP, so you can run agents against it safely.

FAQ

Questions about set_motd

What does the set_motd tool do? +

Set the Message of the Day (MOTD) of the Minecraft server. It is categorised as a Write tool in the OPanel MCP MCP Server, which means it can create or modify data. Consider rate limits to prevent runaway writes.

How do I enforce a policy on set_motd? +

Register the OPanel MCP server in PolicyLayer and add a rule for set_motd: 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 OPanel MCP. Nothing to install.

What risk level is set_motd? +

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

Can I rate-limit set_motd? +

Yes. Add a rate_limit block to the set_motd 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 set_motd completely? +

Set action: deny in the PolicyLayer policy for set_motd. 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 set_motd? +

set_motd is provided by the OPanel MCP server (opanel-mc/opanel-mcp). PolicyLayer sits as a proxy in front of this server to enforce policies before tool calls reach the server.