files_complete_upload_external · Slack MCP: Risk & Policy

WHAT IT DOES

What files_complete_upload_external does on Slack

AI agents use files_complete_upload_external 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 files_complete_upload_external needs a policy

The tool completes an external file upload to Slack, creating or storing data persistibly. This is a Write operation (data creation/modification) rather than Read (no retrieval), Execute (no code execution), Destructive (not irreversible deletion), or Financial (no money movement).

From the tool's definition Tool name 'files_complete_upload_external' indicates file upload completion; sibling context shows this server provides full access to Slack files, channels, and messages via 220 tools.

Attacks that exploit this kind of access

Recommended rule Ready

Verdict

files_complete_upload_external Rate-limited

files_complete_upload_external 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": {
    "files_complete_upload_external": {
      "limits": [
        {
          "counter": "files_complete_upload_external_rate",
          "window": "minute",
          "max": 30,
          "scope": "grant"
        }
      ]
    }
  }
}

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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 files_complete_upload_external

What does the files_complete_upload_external tool do? +

files_complete_upload_external. 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 files_complete_upload_external? +

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

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

Can I rate-limit files_complete_upload_external? +

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

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

files_complete_upload_external 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.