chat_stop_stream · Slack MCP: Risk & Policy

WHAT IT DOES

What chat_stop_stream does on Slack

AI agents invoke chat_stop_stream to trigger actions in Slack. What it does depends on the arguments the agent supplies, and its effects often reach beyond the immediate call — builds kicked off, notifications sent, workflows started.

WHY IT NEEDS A POLICY

Why chat_stop_stream needs a policy

Stopping a message stream is an irreversible action that halts an in-progress operation. While not destructive in the sense of deleting data, it executes a command that changes system state and interrupts a workflow. It does not merely read or write data reversibly; it terminates an active process.

From the tool's definition Tool name 'chat_stop_stream' and description 'Stop an AI assistant streaming message' indicate an action that interrupts or terminates an ongoing operation (streaming message from an AI assistant). This is an external operation trigger.

Attacks that exploit this kind of access

Recommended rule Ready

Verdict

chat_stop_stream Rate-limited

chat_stop_stream stays usable, but rate-capped — a runaway agent can't fire it dozens of times a minute. Everything else on the server is denied unless you say otherwise.

View as policy code

policy.json

{
  "version": "1",
  "default": "deny",
  "tools": {
    "chat_stop_stream": {
      "limits": [
        {
          "counter": "chat_stop_stream_rate",
          "window": "minute",
          "max": 10,
          "scope": "grant"
        }
      ]
    }
  }
}

RATE-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 chat_stop_stream

What does the chat_stop_stream tool do? +

Stop an AI assistant streaming message. It is categorised as a Execute tool in the Slack MCP Server, which means it can trigger actions or run processes. Use rate limits and argument validation.

How do I enforce a policy on chat_stop_stream? +

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

chat_stop_stream is a Execute tool with high risk. Execute tools should be rate-limited and have argument validation enabled.

Can I rate-limit chat_stop_stream? +

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

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

chat_stop_stream 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.