files_get_upload_url_external

A write tool on the Slack MCP server.

SERVERSlack SOURCEkarbassi/slack-mcp

Medium RISK CLASS

Category Write

Parameters 00 required

Recommended Rate-limitedsee the rule below

Registry record Grade F, identity unverified Pull the record →

This record as markdown: /tools/karbassi-slack-mcp/files-get-upload-url-external.md

WHAT IT DOES

What files_get_upload_url_external does on Slack

AI agents use files_get_upload_url_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.

RISK

Why files_get_upload_url_external is rated Medium

The tool name indicates it retrieves an upload URL for external files, which is part of a write workflow (uploading files to Slack). Getting an upload URL is a precursor to writing data. The description is empty, lowering confidence. Severity is medium as misuse could enable unauthorized file uploads, but this step alone only generates a URL rather than completing the upload.

From the tool's definition Tool name 'files_get_upload_url_external' suggests obtaining a URL for external file upload, implying a write/upload operation preparation step.

Attacks that exploit this kind of access

RECOMMENDED RULE

The rule that runs files_get_upload_url_external safely

PolicyLayer is an MCP gateway: it sits between your AI agents and Slack, and checks every tool call against a rule you set before the call runs. Nothing changes on the server itself. For files_get_upload_url_external, this is the rule to start with:

files_get_upload_url_external Rate-limited

files_get_upload_url_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_get_upload_url_external": {
      "limits": [
        {
          "counter": "files_get_upload_url_external_rate",
          "window": "minute",
          "max": 30,
          "scope": "grant"
        }
      ]
    }
  }
}

LIMIT THIS TOOL → Instant setup, no code required.

The button opens the PolicyLayer dashboard: create your workspace, connect Slack, apply this rule, and every files_get_upload_url_external call is checked against it from then on.

FAQ

Questions about files_get_upload_url_external

What does the files_get_upload_url_external tool do? +

files_get_upload_url_external is a write tool on the Slack MCP server. 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_get_upload_url_external? +

Register the Slack MCP server in PolicyLayer and add a rule for files_get_upload_url_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_get_upload_url_external? +

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

Can I rate-limit files_get_upload_url_external? +

Yes. Add a rate_limit block to the files_get_upload_url_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_get_upload_url_external completely? +

Set action: deny in the PolicyLayer policy for files_get_upload_url_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_get_upload_url_external? +

files_get_upload_url_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.

KEEP EXPLORING

More on Slack, and thousands of servers like it.

This server

All 233 Slack tools →

Across the catalogue

scaffold_project_files on Stitch MCP Server → The MCP Attack Database →

Guides

Govern customer-ops agents →Argument validation →Scoped token →