supabase_create_user · Supabase MCP Server MCP

WHAT IT DOES

What supabase_create_user does on Supabase MCP Server

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

WHY IT NEEDS A POLICY

Why supabase_create_user needs a policy

This tool creates new user accounts, which is a reversible write operation. It modifies the user database by adding new entries. Severity is high because an AI agent with this capability could create unauthorized user accounts, grant unintended access, or perform account takeover preparation. The requirement for a service key indicates elevated permissions are needed, amplifying risk.

From the tool's definition Tool name 'supabase_create_user' and description 'Create a new user with the admin API (service key required)' explicitly indicates creation of new user accounts in the Supabase authentication system.

Risk signalsAdmin/system-level operation

Attacks that exploit this kind of access

Recommended rule Ready

Verdict

supabase_create_user Rate-limited

supabase_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": {
    "supabase_create_user": {
      "limits": [
        {
          "counter": "supabase_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 Supabase MCP Server, so you can run agents against it safely.

FAQ

Questions about supabase_create_user

What does the supabase_create_user tool do? +

Create a new user with the admin API (service key required). It is categorised as a Write tool in the Supabase 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 supabase_create_user? +

Register the Supabase MCP Server MCP server in PolicyLayer and add a rule for supabase_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 Supabase MCP Server. Nothing to install.

What risk level is supabase_create_user? +

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

Can I rate-limit supabase_create_user? +

Yes. Add a rate_limit block to the supabase_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 supabase_create_user completely? +

Set action: deny in the PolicyLayer policy for supabase_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 supabase_create_user? +

supabase_create_user is provided by the Supabase MCP Server MCP server (sweir1/supabase-mcp-server). PolicyLayer sits as a proxy in front of this server to enforce policies before tool calls reach the server.