stars_add · Slack MCP: Risk & Policy

WHAT IT DOES

What stars_add does on Slack

AI agents use stars_add 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 stars_add needs a policy

Starring/bookmarking is a reversible write operation that modifies user metadata or item state in Slack without deleting or overwriting data. While the description is empty (reducing confidence), the naming convention clearly indicates a create/modify action. Severity is medium because unintended starring could clutter a user's saved items but is easily undone and has no financial or destructive impact.

From the tool's definition Tool name 'stars_add' indicates adding a star/bookmark to a Slack item (message, file, or channel). The 'add' verb indicates a write operation that creates a new association or flag.

Attacks that exploit this kind of access

Recommended rule Ready

Verdict

stars_add Rate-limited

stars_add 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": {
    "stars_add": {
      "limits": [
        {
          "counter": "stars_add_rate",
          "window": "minute",
          "max": 30,
          "scope": "grant"
        }
      ]
    }
  }
}

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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 stars_add

What does the stars_add tool do? +

stars_add. 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 stars_add? +

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

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

Can I rate-limit stars_add? +

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

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

stars_add 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.