send_message_with_file

THE RISK

Medium Risk

Why send_message_with_file needs a policy

This tool creates new data (a Discord message with file attachment) in a channel, which is a Write operation. It is not Read (no data retrieval), not Execute (does not run code or trigger arbitrary operations), not Destructive (messages are deletable), and not Financial.

From the tool's definition Tool name 'send_message_with_file' and description 'Send a message with a file attachment to a channel' indicate creation of new content (a message with attachment) that is reversible (messages can be deleted).

Documented attack patterns abuse exactly the kind of access send_message_with_file gives an agent:

POLICY

How to control send_message_with_file

PolicyLayer is an MCP gateway — it sits between your AI agents and Discord, and nothing reaches the server without passing your rules. This is the rule we recommend for send_message_with_file:

policy.json

{
  "version": "1",
  "default": "deny",
  "tools": {
    "send_message_with_file": {
      "limits": [
        {
          "counter": "send_message_with_file_rate",
          "window": "minute",
          "max": 30,
          "scope": "grant"
        }
      ]
    }
  }
}

send_message_with_file 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.

Create a free account and register Discord — nothing to install.
Add this policy — paste it, or build it visually.
Point your MCP client (Claude, Cursor, anything) at your gateway URL.

LIMIT THIS TOOL →

Free to start. No card required.

EXPLORE

Related tools and policies

More Discord tools

Destructive bulk_delete_messages Delete multiple messages from a channel at once (2-100 messages). Only works on messages l Destructive delete_automod_rule Delete an auto-moderation rule from the Discord server. Destructive delete_channel Delete a channel from the Discord server. Channel name is fuzzy-matched. Destructive delete_command Delete an application (slash) command. Destructive delete_emoji Remove a custom emoji from the server by name or ID. Destructive delete_event Delete a scheduled event from the Discord server. Destructive delete_forum_tag Remove a tag from a forum channel. Destructive delete_integration Remove an integration from the server by its ID.

All 139 Discord tools →

Write tools on other servers

M-Team MCP Server download_torrent YouTube MCP Server generate_video_title Android Forensics ADB MCP Server combine_reports 0xarchive web3_signup

Go deeper

The MCP Attack Database → Documented attack patterns against MCP deployments — and the policies that stop them.
Argument validation → Checking tool call arguments against schema and policy before they run.
Scoped token → Per-person credentials that grant a defined subset of servers and tools.
Rate Limiting MCP Tool Calls: A Practical Guide →
MCP Security: Why Prompt Guardrails Aren't Enough →

FAQ

Questions about send_message_with_file

What does the send_message_with_file tool do? +

Send a message with a file attachment to a channel. The file can be specified by URL. It is categorised as a Write tool in the Discord MCP Server, which means it can create or modify data. Consider rate limits to prevent runaway writes.

How do I enforce a policy on send_message_with_file? +

Register the Discord MCP server in PolicyLayer and add a rule for send_message_with_file: 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 Discord. Nothing to install.

What risk level is send_message_with_file? +

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

Can I rate-limit send_message_with_file? +

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

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

send_message_with_file is provided by the Discord MCP server (hardheadhackerhead/discord-mcp). PolicyLayer sits as a proxy in front of this server to enforce policies before tool calls reach the server.

Enforce policy on every Discord tool call.

Start from Discord, add the rest of your stack, and see everything your agents can call. Then put policy on all of it.

CHECK YOUR STACK →