memory_unlock · Mementos MCP: Risk & Policy

WHAT IT DOES

What memory_unlock does on Mementos

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

WHY IT NEEDS A POLICY

Why memory_unlock needs a policy

The tool performs a state modification (releasing a lock) that is reversible and has no permanent destructive effect. It does not delete data, execute arbitrary code, or move money. Lock release is a standard synchronization primitive that facilitates writes but is itself a write operation on lock state.

From the tool's definition Tool description: 'Release a memory write lock.' This is a lock-management operation that modifies the state of a memory lock by releasing it, enabling subsequent write operations.

Attacks that exploit this kind of access

Recommended rule Ready

Verdict

memory_unlock Rate-limited

memory_unlock 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": {
    "memory_unlock": {
      "limits": [
        {
          "counter": "memory_unlock_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 Mementos, so you can run agents against it safely.

FAQ

Questions about memory_unlock

What does the memory_unlock tool do? +

Release a memory write lock. It is categorised as a Write tool in the Mementos MCP Server, which means it can create or modify data. Consider rate limits to prevent runaway writes.

How do I enforce a policy on memory_unlock? +

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

What risk level is memory_unlock? +

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

Can I rate-limit memory_unlock? +

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

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

memory_unlock is provided by the Mementos MCP server (@hasna/mementos). PolicyLayer sits as a proxy in front of this server to enforce policies before tool calls reach the server.