Add users to a group. Args: group_name: Name of the group user_ids: List of user IDs to add Returns: Result of adding users
AI agents use add_users_to_group 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.
This tool creates or modifies group membership by adding users to a group, which is a reversible write operation. It does not delete data (Destructive), move money (Financial), or execute code with side effects beyond the intended modification (Execute).
From the tool's definition Tool name and description explicitly state 'Add users to a group' with parameters for group_name and user_ids. The verb 'add' combined with modifying group membership indicates reversible data modification.
Documented attack patterns abuse exactly the kind of access add_users_to_group gives an agent:
PolicyLayer is an MCP gateway — it sits between your AI agents and Ludus FastMCP, and nothing reaches the server without passing your rules. This is the rule we recommend for add_users_to_group:
{
"version": "1",
"default": "deny",
"tools": {
"add_users_to_group": {
"limits": [
{
"counter": "add_users_to_group_rate",
"window": "minute",
"max": 30,
"scope": "grant"
}
]
}
}
}add_users_to_group 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.
Free to start. No card required.
Add users to a group. Args: group_name: Name of the group user_ids: List of user IDs to add Returns: Result of adding users. 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.
Register the Ludus Fast MCP server in PolicyLayer and add a rule for add_users_to_group: 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.
add_users_to_group is a Write tool with medium risk. Write tools should be rate-limited to prevent accidental bulk modifications.
Yes. Add a rate_limit block to the add_users_to_group 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.
Set action: deny in the PolicyLayer policy for add_users_to_group. 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.
add_users_to_group 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.
Deterministic rules across all 201 Ludus FastMCP tools. Per-identity grants. Full audit log. Live in minutes. Nothing to install.
Free to start. No card required.
201 Ludus FastMCP tools catalogued and risk-classified — across an index of 42,500+ MCP servers.