create_user · PostgreSQL MCP Server MCP: Risk & Policy

WHAT IT DOES

What create_user does on PostgreSQL MCP Server

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

WHY IT NEEDS A POLICY

Why create_user needs a policy

Creating a database user is a reversible write operation that modifies database security configuration and user management state. It does not execute arbitrary code (Execute), delete data (Destructive), or move money (Financial).

From the tool's definition Tool name: 'create_user'. Description: 'Create a new database user'. This operation creates a new database user account, which modifies the authentication and access control state of the PostgreSQL database.

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"
        }
      ]
    }
  }
}

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Instant setup, no code required.

PolicyLayer is an MCP gateway: every tool call is checked against your rule before it reaches PostgreSQL MCP Server, so you can run agents against it safely.

FAQ

Questions about create_user

What does the create_user tool do? +

Create a new database user. It is categorised as a Write tool in the PostgreSQL MCP Server 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 PostgreSQL MCP Server 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 PostgreSQL MCP Server. 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 PostgreSQL MCP Server MCP server (reckersai/mcpg). PolicyLayer sits as a proxy in front of this server to enforce policies before tool calls reach the server.