memory_update_rule · Claude Memory MCP: Risk & Policy

WHAT IT DOES

What memory_update_rule does on Claude Memory MCP

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

WHY IT NEEDS A POLICY

Why memory_update_rule needs a policy

This tool modifies rules that enforce constraints on memory operations within a project context. While it creates side effects by changing rule behavior, the change is reversible (a rule can be updated again). This places it in the Write category rather than Execute or Destructive.

From the tool's definition The tool description states 'Update an existing mandatory or forbidden rule by its id.' The verb 'Update' indicates modification of existing data (rules) without deletion or irreversible destruction.

Attacks that exploit this kind of access

Recommended rule Ready

Verdict

memory_update_rule Rate-limited

memory_update_rule 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_update_rule": {
      "limits": [
        {
          "counter": "memory_update_rule_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 Claude Memory MCP, so you can run agents against it safely.

FAQ

Questions about memory_update_rule

What does the memory_update_rule tool do? +

Update an existing mandatory or forbidden rule by its id. It is categorised as a Write tool in the Claude Memory MCP 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_update_rule? +

Register the Claude Memory MCP server in PolicyLayer and add a rule for memory_update_rule: 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 Claude Memory MCP. Nothing to install.

What risk level is memory_update_rule? +

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

Can I rate-limit memory_update_rule? +

Yes. Add a rate_limit block to the memory_update_rule 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_update_rule completely? +

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

memory_update_rule is provided by the Claude Memory MCP server (navid-kianfar/claude-memory-mcp). PolicyLayer sits as a proxy in front of this server to enforce policies before tool calls reach the server.