create-user · Users MCP: Risk & Policy

WHAT IT DOES

What create-user does on Users

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

WHY IT NEEDS A POLICY

Why create-user needs a policy

This tool creates new user records, which is a reversible write operation. Severity is medium because creating unauthorized users could compromise system access control and user management integrity, but the operation is not destructive (can be undone by deletion) and carries no financial impact. The confidence is high given the explicit language in both the tool name and description.

From the tool's definition Tool name 'create-user' and description 'Create a new user in the database' explicitly indicate data creation. The server description confirms CRUD operations on users stored in a JSON file.

Attacks that exploit this kind of access

Recommended rule Ready

Verdict

create-user Rate-limited

create-user 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": {
    "create-user": {
      "limits": [
        {
          "counter": "create-user_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 Users, so you can run agents against it safely.

FAQ

Questions about create-user

What does the create-user tool do? +

Create a new user in the database. It is categorised as a Write tool in the Users MCP Server, which means it can create or modify data. Consider rate limits to prevent runaway writes.

How do I enforce a policy on create-user? +

Register the Users MCP server in PolicyLayer and add a rule for create-user: 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 Users. Nothing to install.

What risk level is create-user? +

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

Can I rate-limit create-user? +

Yes. Add a rate_limit block to the create-user 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 create-user completely? +

Set action: deny in the PolicyLayer policy for create-user. 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 create-user? +

create-user is provided by the Users MCP server (stormdotcom/mcp-server). PolicyLayer sits as a proxy in front of this server to enforce policies before tool calls reach the server.