files_share_legacy · Slack MCP: Risk & Policy

WHAT IT DOES

What files_share_legacy does on Slack

AI agents use files_share_legacy 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_share_legacy needs a policy

This tool creates a new sharing relationship between a file and a channel, which is a reversible modification of data/permissions. It does not delete data (ruling out Destructive), does not execute arbitrary code (ruling out Execute), and does not involve financial transactions (ruling out Financial).

From the tool's definition Tool name contains 'share' and description states 'Share a file to a channel', indicating it modifies access permissions and channel state by distributing a file resource.

Attacks that exploit this kind of access

Recommended rule Ready

Verdict

files_share_legacy Rate-limited

files_share_legacy 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_share_legacy": {
      "limits": [
        {
          "counter": "files_share_legacy_rate",
          "window": "minute",
          "max": 30,
          "scope": "grant"
        }
      ]
    }
  }
}

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 files_share_legacy

What does the files_share_legacy tool do? +

Share a file to a channel (legacy undocumented). 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_share_legacy? +

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

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

Can I rate-limit files_share_legacy? +

Yes. Add a rate_limit block to the files_share_legacy 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_share_legacy completely? +

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

files_share_legacy 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.