update_memory · OpenMemBrain MCP: Risk & Policy

WHAT IT DOES

What update_memory does on OpenMemBrain

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

WHY IT NEEDS A POLICY

Why update_memory needs a policy

This tool creates or modifies data reversibly by updating memory records. While it re-validates through policy checks, the core function is to persistently alter stored memory artifacts. This is reversible (as opposed to deletion), making it Write rather than Destructive.

From the tool's definition Tool description explicitly states 'Update the content, type, scope, or tags of a saved memory', indicating modification of stored data. The term 'update' combined with modifying multiple attributes (content, type, scope, tags) confirms write-level capability.

Attacks that exploit this kind of access

Recommended rule Ready

Verdict

update_memory Rate-limited

update_memory 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": {
    "update_memory": {
      "limits": [
        {
          "counter": "update_memory_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 OpenMemBrain, so you can run agents against it safely.

FAQ

Questions about update_memory

What does the update_memory tool do? +

Update the content, type, scope, or tags of a saved memory. The updated content is re-validated through policy checks. It is categorised as a Write tool in the OpenMemBrain MCP Server, which means it can create or modify data. Consider rate limits to prevent runaway writes.

How do I enforce a policy on update_memory? +

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

What risk level is update_memory? +

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

Can I rate-limit update_memory? +

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

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

update_memory is provided by the OpenMemBrain MCP server (mohamadalhusseinie/openmembrain). PolicyLayer sits as a proxy in front of this server to enforce policies before tool calls reach the server.