knowledge_write · Loom MCP: Risk & Policy

WHAT IT DOES

What knowledge_write does on Loom

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

WHY IT NEEDS A POLICY

Why knowledge_write needs a policy

The tool creates or modifies entity pages (Write operation) rather than permanently deleting them. While 'REPLACES' suggests overwriting, the operation is reversible—the previous state could theoretically be recovered or the page modified again. This is distinct from Destructive operations which are irreversible.

From the tool's definition Tool description states 'Upsert an entity page by slug' and 'body REPLACES by default', indicating reversible creation or modification of data.

Attacks that exploit this kind of access

Recommended rule Ready

Verdict

knowledge_write Rate-limited

knowledge_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": {
    "knowledge_write": {
      "limits": [
        {
          "counter": "knowledge_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 Loom, so you can run agents against it safely.

FAQ

Questions about knowledge_write

What does the knowledge_write tool do? +

Upsert an entity page by slug. On an existing slug: body REPLACES by default. It is categorised as a Write tool in the Loom MCP Server, which means it can create or modify data. Consider rate limits to prevent runaway writes.

How do I enforce a policy on knowledge_write? +

Register the Loom MCP server in PolicyLayer and add a rule for knowledge_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 Loom. Nothing to install.

What risk level is knowledge_write? +

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

Can I rate-limit knowledge_write? +

Yes. Add a rate_limit block to the knowledge_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 knowledge_write completely? +

Set action: deny in the PolicyLayer policy for knowledge_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 knowledge_write? +

knowledge_write is provided by the Loom MCP server (jbarket/loom). PolicyLayer sits as a proxy in front of this server to enforce policies before tool calls reach the server.