update_document · Ai Brain MCP: Risk & Policy

WHAT IT DOES

What update_document does on Ai Brain

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

WHY IT NEEDS A POLICY

Why update_document needs a policy

This tool creates or modifies data reversibly without deleting it, fitting the Write category. Severity is medium because unauthorized updates to knowledge base documents could corrupt information or introduce false data, but the effect is reversible (documents can be restored or corrected).

From the tool's definition Tool name 'update_document' and description 'Update a document' indicate modification of existing data. The server context describes a knowledge base with Markdown notes stored in a self-hosted system.

Attacks that exploit this kind of access

Recommended rule Ready

Verdict

update_document Rate-limited

update_document 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": {
    "update_document": {
      "limits": [
        {
          "counter": "update_document_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 Ai Brain, so you can run agents against it safely.

FAQ

Questions about update_document

What does the update_document tool do? +

Update a document. It is categorised as a Write tool in the Ai Brain MCP Server, which means it can create or modify data. Consider rate limits to prevent runaway writes.

How do I enforce a policy on update_document? +

Register the Ai Brain MCP server in PolicyLayer and add a rule for update_document: 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 Ai Brain. Nothing to install.

What risk level is update_document? +

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

Can I rate-limit update_document? +

Yes. Add a rate_limit block to the update_document 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 update_document completely? +

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

update_document is provided by the Ai Brain MCP server (thejoshgriffith/ai-brain). PolicyLayer sits as a proxy in front of this server to enforce policies before tool calls reach the server.