write_memory · Structured-sh MCP: Risk & Policy

WHAT IT DOES

What write_memory does on Structured-sh

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

WHY IT NEEDS A POLICY

Why write_memory needs a policy

This tool creates or modifies data in a structured memory store (Parquet format). The effects are reversible—records can be deleted via delete_memory—so it does not qualify as Destructive. The operation is a data write without executing code, running commands, or causing financial transactions.

From the tool's definition Tool is described as 'Write structured records to a memory' with automatic buffering and flushing to Parquet. The action is reversible via the sibling tool 'delete_memory' that exists on the same server.

Attacks that exploit this kind of access

Recommended rule Ready

Verdict

write_memory Rate-limited

write_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": {
    "write_memory": {
      "limits": [
        {
          "counter": "write_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 Structured-sh, so you can run agents against it safely.

FAQ

Questions about write_memory

What does the write_memory tool do? +

Write structured records to a memory. Records are buffered and automatically flushed to Parquet. It is categorised as a Write tool in the Structured-sh MCP Server, which means it can create or modify data. Consider rate limits to prevent runaway writes.

How do I enforce a policy on write_memory? +

Register the Structured-sh MCP server in PolicyLayer and add a rule for write_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 Structured-sh. Nothing to install.

What risk level is write_memory? +

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

Can I rate-limit write_memory? +

Yes. Add a rate_limit block to the write_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 write_memory completely? +

Set action: deny in the PolicyLayer policy for write_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 write_memory? +

write_memory is provided by the Structured-sh MCP server (structured-sh/structured). PolicyLayer sits as a proxy in front of this server to enforce policies before tool calls reach the server.