memory_synthesize · Mementos MCP: Risk & Policy

WHAT IT DOES

What memory_synthesize does on Mementos

AI agents use memory_synthesize 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_synthesize needs a policy

The tool analyzes the memory corpus and then applies consolidations, meaning it rewrites or merges existing memory entries. This is a Write operation (modifying data) rather than purely Read. However, since consolidations could irreversibly alter or collapse distinct memory entries (losing nuance or granularity), there is a borderline Destructive aspect.

From the tool's definition 'propose and apply consolidations' and 'find redundancies' — the tool actively modifies the memory corpus by consolidating/merging existing memories

Attacks that exploit this kind of access

Recommended rule Ready

Verdict

memory_synthesize Rate-limited

memory_synthesize 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_synthesize": {
      "limits": [
        {
          "counter": "memory_synthesize_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_synthesize

What does the memory_synthesize tool do? +

Run ALMA synthesis: analyze memory corpus, find redundancies, propose and apply consolidations. 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_synthesize? +

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

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

Can I rate-limit memory_synthesize? +

Yes. Add a rate_limit block to the memory_synthesize 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_synthesize completely? +

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

memory_synthesize 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.