register_user · WaniKani MCP Server MCP: Risk & Policy

WHAT IT DOES

What register_user does on WaniKani MCP Server

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

WHY IT NEEDS A POLICY

Why register_user needs a policy

This tool creates a new user account and stores authentication credentials (WaniKani API key). While this is a reversible Write operation (accounts can typically be deleted), the sensitive nature of storing API keys and the potential for persistent account creation elevates severity to medium.

From the tool's definition Tool name 'register_user' and description 'Register a new user with their WaniKani API key to get MCP key' indicates creating a new user record and storing credentials.

Attacks that exploit this kind of access

Recommended rule Ready

Verdict

register_user Rate-limited

register_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": {
    "register_user": {
      "limits": [
        {
          "counter": "register_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 WaniKani MCP Server, so you can run agents against it safely.

FAQ

Questions about register_user

What does the register_user tool do? +

Register a new user with their WaniKani API key to get MCP key. It is categorised as a Write tool in the WaniKani 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 register_user? +

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

What risk level is register_user? +

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

Can I rate-limit register_user? +

Yes. Add a rate_limit block to the register_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 register_user completely? +

Set action: deny in the PolicyLayer policy for register_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 register_user? +

register_user is provided by the WaniKani MCP Server MCP server (jackedney/wanikani-mcp). PolicyLayer sits as a proxy in front of this server to enforce policies before tool calls reach the server.