memento_graph · Memento MCP: Risk & Policy

WHAT IT DOES

What memento_graph does on Memento

AI agents use memento_graph 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_graph needs a policy

The tool operates on a SQLite temporal graph used for persistent memory storage. Management of a graph data structure typically involves write operations (adding/updating nodes, edges, properties). While the truncated description limits certainty, the verb 'manage' combined with the server's purpose of persistent autonomous memory suggests this tool can modify the graph state.

From the tool's definition Tool is named 'memento_graph' with description 'Manage the Project Memory Graph. Actions:' — 'Manage' indicates modification and mutation of graph data structure.

Attacks that exploit this kind of access

Recommended rule Ready

Verdict

memento_graph Rate-limited

memento_graph 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_graph": {
      "limits": [
        {
          "counter": "memento_graph_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_graph

What does the memento_graph tool do? +

Manage the Project Memory Graph. Actions:. 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_graph? +

Register the Memento MCP server in PolicyLayer and add a rule for memento_graph: 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_graph? +

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

Can I rate-limit memento_graph? +

Yes. Add a rate_limit block to the memento_graph 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_graph completely? +

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

memento_graph 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.