workflows_step_completed · Slack MCP: Risk & Policy

WHAT IT DOES

What workflows_step_completed does on Slack

AI agents invoke workflows_step_completed 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 workflows_step_completed needs a policy

This tool triggers an external workflow state change by marking a step as completed, which causes downstream workflow execution to proceed. It is an action that affects the state of an external system (Slack Workflows), making it an Execute-category tool. Misuse could cause unintended workflow progressions, hence medium severity.

From the tool's definition Indicate a workflow step has been completed successfully

Attacks that exploit this kind of access

Recommended rule Ready

Verdict

workflows_step_completed Rate-limited

workflows_step_completed 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": {
    "workflows_step_completed": {
      "limits": [
        {
          "counter": "workflows_step_completed_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 workflows_step_completed

What does the workflows_step_completed tool do? +

Indicate a workflow step has been completed successfully. 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 workflows_step_completed? +

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

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

Can I rate-limit workflows_step_completed? +

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

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

workflows_step_completed 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.