Send a text message to a text channel OR a voice channel (voice channels have built-in text chat). Supports both regular text channels and voice channel text chats. Channel name is fuzzy-matched. IMPORTANT: Before calling this tool, use list_channels to find the exact channel name.
AI agents use send_message to create or update resources in Discord — usually the action step of a workflow, after the agent has gathered context. Every call changes real data in your Discord environment.
This tool creates new messages in Discord channels, which is a Write operation. While the severity is not critical because message posting is a standard Discord function, it becomes medium-risk in an AI agent context due to potential for sending unintended messages at scale, impersonation risks, or spam. The fuzzy channel matching introduces additional risk of targeting the wrong channel.
From the tool's definition Tool description states "Send a text message to a text channel OR a voice channel" - this creates/posts new data (messages) in a Discord server. The action is reversible (messages can be deleted), distinguishing it from Destructive.
Documented attack patterns abuse exactly the kind of access send_message gives an agent:
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:
{
"version": "1",
"default": "deny",
"tools": {
"send_message": {
"limits": [
{
"counter": "send_message_rate",
"window": "minute",
"max": 30,
"scope": "grant"
}
]
}
}
}send_message 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.
Free to start. No card required.
Send a text message to a text channel OR a voice channel (voice channels have built-in text chat). Supports both regular text channels and voice channel text chats. Channel name is fuzzy-matched. IMPORTANT: Before calling this tool, use list_channels to find the exact channel name. 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.
Register the Discord MCP server in PolicyLayer and add a rule for send_message: 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.
send_message is a Write tool with medium risk. Write tools should be rate-limited to prevent accidental bulk modifications.
Yes. Add a rate_limit block to the send_message 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.
Set action: deny in the PolicyLayer policy for send_message. 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.
send_message 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.
Start from Discord, add the rest of your stack, and see everything your agents can call. Then put policy on all of it.
Free to start. No card required.
139 Discord tools catalogued and risk-classified — across an index of 43,000+ MCP servers.