memory_write · Claude Memory MCP: Risk & Policy

WHAT IT DOES

What memory_write does on Claude Memory

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

WHY IT NEEDS A POLICY

Why memory_write needs a policy

This tool creates or modifies data (memory entries) in a file, which is reversible via editing or deletion. It has no destructive capability (entries can be overwritten or removed), no code execution, and no financial impact.

From the tool's definition Tool name is 'memory_write' and description states 'Write a value to Claude', indicating it modifies/persists data to a .claude-memory.md file.

Attacks that exploit this kind of access

Recommended rule Ready

Verdict

memory_write Rate-limited

memory_write 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_write": {
      "limits": [
        {
          "counter": "memory_write_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, so you can run agents against it safely.

FAQ

Questions about memory_write

What does the memory_write tool do? +

Write a value to Claude. It is categorised as a Write tool in the Claude Memory 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_write? +

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

What risk level is memory_write? +

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

Can I rate-limit memory_write? +

Yes. Add a rate_limit block to the memory_write 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_write completely? +

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

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