resource_lock · Mementos MCP: Risk & Policy

WHAT IT DOES

What resource_lock does on Mementos

AI agents use resource_lock 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 resource_lock needs a policy

Acquiring a lock modifies the state of a resource by marking it as locked, preventing other agents from accessing it. This is a reversible Write operation (locks can be released), but misuse could cause deadlocks or resource starvation across agents, warranting medium severity.

From the tool's definition "Acquire a lock on any resource (project, memory, entity, agent, connector)"

Attacks that exploit this kind of access

Recommended rule Ready

Verdict

resource_lock Rate-limited

resource_lock 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": {
    "resource_lock": {
      "limits": [
        {
          "counter": "resource_lock_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 resource_lock

What does the resource_lock tool do? +

Acquire a lock on any resource (project, memory, entity, agent, connector). 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 resource_lock? +

Register the Mementos MCP server in PolicyLayer and add a rule for resource_lock: 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 resource_lock? +

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

Can I rate-limit resource_lock? +

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

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

resource_lock 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.