documents · Personal Brain MCP: Risk & Policy

WHAT IT DOES

What documents does on Personal Brain

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

WHY IT NEEDS A POLICY

Why documents needs a policy

The tool supports both read operations (search, list expiring soon) and write operations (add or update). Per the rules, the most severe applicable category is chosen. The ability to add or update highly sensitive personal documents (IDs, legal docs, insurance policies, contracts, titles) makes this a Write tool with high severity, as an AI agent misusing it could tamper with, corrupt, or insert false sensitive…

From the tool's definition 'add or update' alongside storing sensitive document types: 'warranties, manuals, contracts, IDs, titles, insurance policies, legal docs'

Attacks that exploit this kind of access

Recommended rule Ready

Verdict

documents Rate-limited

documents 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": {
    "documents": {
      "limits": [
        {
          "counter": "documents_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 Personal Brain, so you can run agents against it safely.

FAQ

Questions about documents

What does the documents tool do? +

General document directory (warranties, manuals, contracts, IDs, titles, insurance policies, legal docs). Search by name/category/subject, list expiring soon, add or update. It is categorised as a Write tool in the Personal 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 documents? +

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

What risk level is documents? +

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

Can I rate-limit documents? +

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

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

documents is provided by the Personal Brain MCP server (phantomts/personal-brain-mcp). PolicyLayer sits as a proxy in front of this server to enforce policies before tool calls reach the server.