conversations_set_topic · Slack MCP: Risk & Policy

WHAT IT DOES

What conversations_set_topic does on Slack

AI agents use conversations_set_topic 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 conversations_set_topic needs a policy

This tool modifies metadata of a Slack conversation (its topic) but does not delete, destroy, or execute arbitrary code. The change is reversible—a topic can be set again to a different value.

From the tool's definition Tool name is 'conversations_set_topic' and description states 'Set the topic for a conversation.' The verb 'set' indicates modification of existing data (the conversation's topic).

Attacks that exploit this kind of access

Recommended rule Ready

Verdict

conversations_set_topic Rate-limited

conversations_set_topic 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": {
    "conversations_set_topic": {
      "limits": [
        {
          "counter": "conversations_set_topic_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 conversations_set_topic

What does the conversations_set_topic tool do? +

Set the topic for a conversation. 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 conversations_set_topic? +

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

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

Can I rate-limit conversations_set_topic? +

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

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

conversations_set_topic 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.