memento_add_memory · Memento MCP: Risk & Policy

WHAT IT DOES

What memento_add_memory does on Memento

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

WHY IT NEEDS A POLICY

Why memento_add_memory needs a policy

This tool creates or appends new entries to the agent's persistent memory store. While marked deprecated, the core function remains a Write operation—adding data without irreversible deletion.

From the tool's definition Tool name and description indicate 'Add a new memory' which creates/modifies data in the Memento SQLite temporal graph. The action is reversible (memories can be updated or removed), distinguishing it from destructive operations.

Attacks that exploit this kind of access

Recommended rule Ready

Verdict

memento_add_memory Rate-limited

memento_add_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": {
    "memento_add_memory": {
      "limits": [
        {
          "counter": "memento_add_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 Memento, so you can run agents against it safely.

FAQ

Questions about memento_add_memory

What does the memento_add_memory tool do? +

[DEPRECATED] Add a new memory to the Memento provider. It is categorised as a Write tool in the Memento MCP Server, which means it can create or modify data. Consider rate limits to prevent runaway writes.

How do I enforce a policy on memento_add_memory? +

Register the Memento MCP server in PolicyLayer and add a rule for memento_add_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 Memento. Nothing to install.

What risk level is memento_add_memory? +

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

Can I rate-limit memento_add_memory? +

Yes. Add a rate_limit block to the memento_add_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 memento_add_memory completely? +

Set action: deny in the PolicyLayer policy for memento_add_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 memento_add_memory? +

memento_add_memory is provided by the Memento MCP server (joyciakira/memento). PolicyLayer sits as a proxy in front of this server to enforce policies before tool calls reach the server.