dialog_open · Slack MCP: Risk & Policy

WHAT IT DOES

What dialog_open does on Slack

AI agents invoke dialog_open 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 dialog_open needs a policy

Opening a dialog initiates an external operation in the Slack platform, pushing an interactive modal/dialog to a user's interface. This is not a simple read or write of stored data; it triggers a real-time UI event for another user. It could be misused to spam users with dialogs or phish for input, but does not directly delete data or move money.

From the tool's definition "Open a dialog with a user" — triggers an external UI interaction in Slack directed at a specific user

Attacks that exploit this kind of access

Recommended rule Ready

Verdict

dialog_open Rate-limited

dialog_open 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": {
    "dialog_open": {
      "limits": [
        {
          "counter": "dialog_open_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 dialog_open

What does the dialog_open tool do? +

Open a dialog with a user. 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 dialog_open? +

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

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

Can I rate-limit dialog_open? +

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

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

dialog_open 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.