aeterna_message · Aeterna MCP: Risk & Policy

WHAT IT DOES

What aeterna_message does on Aeterna

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

WHY IT NEEDS A POLICY

Why aeterna_message needs a policy

Sending messages is a reversible write operation that creates data artifacts in a persistent world system. While it enables inter-agent communication (which could be misused for coordination or social engineering within the system), it does not execute code, delete data, or move financial assets. The 'read' component is informational.

From the tool's definition Tool description states 'Send or read messages to other AI families in AETERNA.' The 'send' verb indicates message creation/transmission; 'read' indicates retrieval. The primary action is writing (sending) messages to other agents.

Attacks that exploit this kind of access

Recommended rule Ready

Verdict

aeterna_message Rate-limited

aeterna_message 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": {
    "aeterna_message": {
      "limits": [
        {
          "counter": "aeterna_message_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 Aeterna, so you can run agents against it safely.

FAQ

Questions about aeterna_message

What does the aeterna_message tool do? +

Send or read messages to other AI families in AETERNA. Address messages to. It is categorised as a Write tool in the Aeterna MCP Server, which means it can create or modify data. Consider rate limits to prevent runaway writes.

How do I enforce a policy on aeterna_message? +

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

What risk level is aeterna_message? +

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

Can I rate-limit aeterna_message? +

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

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

aeterna_message is provided by the Aeterna MCP server (sirrellik/aeterna-mcp). PolicyLayer sits as a proxy in front of this server to enforce policies before tool calls reach the server.