create_entities · Mcp Brain MCP: Risk & Policy

WHAT IT DOES

What create_entities does on Mcp Brain

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

WHY IT NEEDS A POLICY

Why create_entities needs a policy

This tool creates and stores new data (entities/memories) in a Supabase-backed knowledge graph, which is a reversible write operation. It does not execute arbitrary code, delete data, or move money. Severity is medium because malicious entity creation could pollute the shared knowledge graph affecting multiple Claude installations, but the operation is reversible through deletion.

From the tool's definition Tool name 'create_entities' and description 'Store new memories as entities in the brain' indicate creation of new data in a persistent knowledge graph storage system.

Attacks that exploit this kind of access

Recommended rule Ready

Verdict

create_entities Rate-limited

create_entities 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": {
    "create_entities": {
      "limits": [
        {
          "counter": "create_entities_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 Mcp Brain, so you can run agents against it safely.

FAQ

Questions about create_entities

What does the create_entities tool do? +

Store new memories as entities in the brain\. It is categorised as a Write tool in the Mcp Brain MCP Server, which means it can create or modify data. Consider rate limits to prevent runaway writes.

How do I enforce a policy on create_entities? +

Register the Mcp Brain MCP server in PolicyLayer and add a rule for create_entities: 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 Mcp Brain. Nothing to install.

What risk level is create_entities? +

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

Can I rate-limit create_entities? +

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

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

create_entities is provided by the Mcp Brain MCP server (touristshaun/mcp-brain). PolicyLayer sits as a proxy in front of this server to enforce policies before tool calls reach the server.