users_set_presence · Slack MCP: Risk & Policy

WHAT IT DOES

What users_set_presence does on Slack

AI agents use users_set_presence 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 users_set_presence needs a policy

Setting presence is a write operation that changes user status/state in Slack. While reversible and not destructive, it modifies data. The blast radius is medium because spoofing presence (appearing online/offline when you're not) could be used for social engineering, impersonation, or disrupting team coordination, but the impact is limited to presence status and doesn't directly access sensitive data, delete…

From the tool's definition Tool name is 'users_set_presence' and description states 'Manually set user presence' — this modifies user state (presence status) in Slack, which is a reversible change to user data.

Attacks that exploit this kind of access

Recommended rule Ready

Verdict

users_set_presence Rate-limited

users_set_presence 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": {
    "users_set_presence": {
      "limits": [
        {
          "counter": "users_set_presence_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 users_set_presence

What does the users_set_presence tool do? +

Manually set user presence. 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 users_set_presence? +

Register the Slack MCP server in PolicyLayer and add a rule for users_set_presence: 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 users_set_presence? +

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

Can I rate-limit users_set_presence? +

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

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

users_set_presence 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.