MCP servers that can send a Slack message
6 verified servers expose a tool that can send a Slack message
Slack's write tools ship off by default, so "post this to the channel" is one capability you switch on deliberately. The Slack server handles it; the other team-chat platforms do the same under different tool names.
These verified servers let an agent send a message into a channel or DM, on Slack and the tools that compete with it.
Slack
korotovsky (community)
Community Slack MCP server with smart history, DMs, and search that needs no workspace bot install.
conversations_add_message
conversations_add_message posts into a Slack channel or DM. It ships disabled by default on the server, a deliberate guardrail so an agent can't broadcast until you enable it.
Telegram
chigwell (Eugene Evstafev)
A maintained Telegram MCP server powered by Telethon: read chats, manage groups and contacts, and send or modify messages, media, and more from your agent.
send_messagesend_scheduled_message
On Telegram, send_message reaches a chat or channel, and send_scheduled_message queues one to go out later.
Mattermost
cloud.ru (community)
A maintained MCP server for Mattermost that lets agents work with channels, messages, threads, reactions, users, teams, and files.
post_message
Mattermost's post_message covers the same job for teams on the open-source Slack alternative they host themselves.
Rocket.Chat
enyonee
Community MCP server for Rocket.Chat: read and post messages, manage threads, DMs, files, reactions, and pins across your team chat.
send_message
Rocket.Chat keeps it to a single send_message into a room, another self-hosted option for chat an agent can write to.
Discord MCP
barryyip0625
Maintained community MCP server that lets an agent run a Discord bot: messages, channels, forums, roles, and webhooks.
discord_send_webhook_message
Discord posts through discord_send_webhook_message, delivering via a webhook rather than a full bot user, which is the lighter way in.
ClickUp
ClickUp
ClickUp's official remote MCP server lets agents manage tasks, lists, folders, docs, time tracking, and chat across a workspace.
send_chat_message
ClickUp folds chat into its work tool, so send_chat_message drops a message right where the tasks already live.
What to know
Posting is a write other people see immediately, which is why this server ships its message tool switched off rather than live. An agent reading channels cannot post to them until you turn it on. Add a confirmation step for anything public, and a hallucinated draft cannot reach a shared channel before a human sees it.
There is a continuity angle too. An agent posting a daily standup summary has no way to know it already ran today unless something outside the Slack tool remembers the last message it sent. Without that, it either double-posts or goes quiet.
Questions
- Why is Slack's message tool disabled by default?
- Because posting to a shared channel is irreversible and public. The Slack server makes you opt in to conversations_add_message rather than enabling broadcast by default, so an agent reading channels can't accidentally write to them. Turn it on deliberately, and pair it with a confirmation step for public posts.
- Can an agent post to other chat platforms the same way?
- Yes. Telegram, Mattermost, Rocket.Chat, Discord, and ClickUp all expose a send-message tool. The action is identical; only the tool name and the platform differ, which is why this page lists each one rather than assuming everything is Slack.