add_fact · Alethea World History Engine MCP: Risk & Policy

WHAT IT DOES

What add_fact does on Alethea World History Engine

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

WHY IT NEEDS A POLICY

Why add_fact needs a policy

The tool creates new relationships in the narrative graph and persists changes ('save state'), which is a write operation that modifies the underlying data model. This falls under Write rather than Read (which would only retrieve data) or Destructive (since relationships can be removed/modified later).

From the tool's definition Tool description states 'Create a relationship between two entities AND save state' - the action of creating a relationship and persisting state changes indicates reversible data modification rather than retrieval or destruction.

Attacks that exploit this kind of access

Recommended rule Ready

Verdict

add_fact Rate-limited

add_fact 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_fact": {
      "limits": [
        {
          "counter": "add_fact_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 Alethea World History Engine, so you can run agents against it safely.

FAQ

Questions about add_fact

What does the add_fact tool do? +

Create a relationship between two entities AND save state. It is categorised as a Write tool in the Alethea World History Engine 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_fact? +

Register the Alethea World History Engine MCP server in PolicyLayer and add a rule for add_fact: 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 Alethea World History Engine. Nothing to install.

What risk level is add_fact? +

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

Can I rate-limit add_fact? +

Yes. Add a rate_limit block to the add_fact 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_fact completely? +

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

add_fact is provided by the Alethea World History Engine MCP server (watashicuvu/world-history-engine). PolicyLayer sits as a proxy in front of this server to enforce policies before tool calls reach the server.