functions_complete_success · Slack MCP: Risk & Policy

WHAT IT DOES

What functions_complete_success does on Slack

AI agents invoke functions_complete_success 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 functions_complete_success needs a policy

This tool triggers an external operation (signaling completion of a workflow function to Slack), which causes side effects in Slack's workflow/function execution system. It is not a simple read, nor does it clearly destroy data or move money. 'Execute' best fits because it triggers an external operation whose effects depend on the function context being completed.

From the tool's definition Signal the successful completion of a function

Attacks that exploit this kind of access

Recommended rule Ready

Verdict

functions_complete_success Rate-limited

functions_complete_success 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": {
    "functions_complete_success": {
      "limits": [
        {
          "counter": "functions_complete_success_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 functions_complete_success

What does the functions_complete_success tool do? +

Signal the successful completion of a function. 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 functions_complete_success? +

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

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

Can I rate-limit functions_complete_success? +

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

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

functions_complete_success 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.