add_user

A write tool on the Ludus Fast MCP server.

SERVERLudus FastMCP SOURCEtjnull/ludus-fastmcp

Medium RISK CLASS

Category Write

Parameters 00 required

Recommended Rate-limitedsee the rule below

Registry record Grade F, identity unverified Pull the record →

This record as markdown: /tools/tjnull-ludus-fastmcp/add-user.md

WHAT IT DOES

What add_user does on Ludus FastMCP

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

RISK

Why add_user is rated Medium

Adding a user creates new data or modifies user membership/access configuration in the Ludus cyber range system. This is a Write operation (reversible, no data deletion). Severity is medium rather than high because user addition in a controlled cyber range environment has bounded blast radius—it does not involve financial transactions, data destruction, or direct code execution.

From the tool's definition Tool name is 'add_user' which indicates creation/modification of user records. The description is empty, but the name unambiguously suggests adding a user to a system, which is a reversible write operation.

Attacks that exploit this kind of access

RECOMMENDED RULE

The rule that runs add_user safely

PolicyLayer is an MCP gateway: it sits between your AI agents and Ludus FastMCP, and checks every tool call against a rule you set before the call runs. Nothing changes on the server itself. For add_user, this is the rule to start with:

add_user Rate-limited

add_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": {
    "add_user": {
      "limits": [
        {
          "counter": "add_user_rate",
          "window": "minute",
          "max": 30,
          "scope": "grant"
        }
      ]
    }
  }
}

LIMIT THIS TOOL → Instant setup, no code required.

The button opens the PolicyLayer dashboard: create your workspace, connect Ludus FastMCP, apply this rule, and every add_user call is checked against it from then on.

FAQ

Questions about add_user

What does the add_user tool do? +

add_user is a write tool on the Ludus Fast MCP server. It is categorised as a Write tool in the Ludus FastMCP MCP Server, which means it can create or modify data. Consider rate limits to prevent runaway writes.

How do I enforce a policy on add_user? +

Register the Ludus Fast MCP server in PolicyLayer and add a rule for add_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 Ludus FastMCP. Nothing to install.

What risk level is add_user? +

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

Can I rate-limit add_user? +

Yes. Add a rate_limit block to the add_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 add_user completely? +

Set action: deny in the PolicyLayer policy for add_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 add_user? +

add_user is provided by the Ludus Fast MCP server (tjnull/ludus-fastmcp). PolicyLayer sits as a proxy in front of this server to enforce policies before tool calls reach the server.

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