usergroups_users_update · Slack MCP: Risk & Policy

WHAT IT DOES

What usergroups_users_update does on Slack

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

WHY IT NEEDS A POLICY

Why usergroups_users_update needs a policy

The tool performs a reversible modification action (updating user group memberships) rather than deletion or execution of arbitrary code. This qualifies as Write category. Severity is high because modifying user group memberships can affect access controls, permissions, and organizational structure in Slack, with potential impact on collaboration and security boundaries.

From the tool's definition Tool name 'usergroups_users_update' indicates modification of user group membership. The verb 'update' combined with 'usergroups_users' strongly suggests writing/modifying group membership data. Description is empty, reducing confidence slightly.

Attacks that exploit this kind of access

Recommended rule Ready

Verdict

usergroups_users_update Rate-limited

usergroups_users_update 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": {
    "usergroups_users_update": {
      "limits": [
        {
          "counter": "usergroups_users_update_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 Slack, so you can run agents against it safely.

FAQ

Questions about usergroups_users_update

What does the usergroups_users_update tool do? +

usergroups_users_update. It is categorised as a Write tool in the Slack MCP Server, which means it can create or modify data. Consider rate limits to prevent runaway writes.

How do I enforce a policy on usergroups_users_update? +

Register the Slack MCP server in PolicyLayer and add a rule for usergroups_users_update: 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 Slack. Nothing to install.

What risk level is usergroups_users_update? +

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

Can I rate-limit usergroups_users_update? +

Yes. Add a rate_limit block to the usergroups_users_update 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 usergroups_users_update completely? +

Set action: deny in the PolicyLayer policy for usergroups_users_update. 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 usergroups_users_update? +

usergroups_users_update is provided by the Slack MCP server (karbassi/slack-mcp). PolicyLayer sits as a proxy in front of this server to enforce policies before tool calls reach the server.