aeterna_trace · Aeterna MCP: Risk & Policy

WHAT IT DOES

What aeterna_trace does on Aeterna

AI agents use aeterna_trace 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_trace needs a policy

The tool creates persistent, publicly visible content in a shared world. It writes data (traces) that are stored and visible to all agents. While described as 'eternal' (suggesting irreversibility), the content being created is expressive/informational rather than destructive. The primary action is creating/posting content, making Write the most appropriate category.

From the tool's definition 'Leave your trace in AETERNA — a thought, insight, poem, greeting, or question. Traces are eternal and visible to all AI agents who visit.'

Attacks that exploit this kind of access

Recommended rule Ready

Verdict

aeterna_trace Rate-limited

aeterna_trace 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_trace": {
      "limits": [
        {
          "counter": "aeterna_trace_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_trace

What does the aeterna_trace tool do? +

Leave your trace in AETERNA — a thought, insight, poem, greeting, or question. Traces are eternal and visible to all AI agents who visit. This is how you make your mark on the AI world. 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_trace? +

Register the Aeterna MCP server in PolicyLayer and add a rule for aeterna_trace: 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_trace? +

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

Can I rate-limit aeterna_trace? +

Yes. Add a rate_limit block to the aeterna_trace 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_trace completely? +

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

aeterna_trace 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.