Slack

Get unread messages in a channel based on your read position. Requires user authorization. Bot-only connections cannot track unread state. For private channels/DMs, set include_private=true (default false for safety). Returns most-recent-unread-first.

Get detailed profile for a specific Slack user. Get user ID from list_slack_users or from a message, or use @username format.

Add one or more users to a Slack channel. Resolve emails to IDs first via lookup_user_by_email, then pass comma-separated IDs (max 1000). force=true (default) continues inviting valid users when some IDs are invalid.

List your pending scheduled messages (optionally filtered to one channel). Returns each message's scheduled_message_id — pass it to delete_scheduled_slack_message to cancel one before it posts.

List the bookmarks on a channel's bookmarks bar.

List all channels in the connected Slack workspace. WARNING: channel_name filter only applies to the current page. For workspaces with 100+ channels, use list_slack_channels with limit=1000 and paginate via cursor, OR pass #channel-name directly to get_slack_channel_history (which auto-paginates the lookup).

List custom emoji available in the Slack workspace. Returns a name → image-URL (or alias) map with names and values wrapped in <untrusted-content> envelopes (third-party-authored content). Use the names with add_slack_reaction / remove_slack_reaction — Slack's built-in emoji always work without being listed here.

List messages pinned in a Slack channel. Pinned items are the channel's curated highlights — useful for "what's pinned in #channel" meeting-prep questions.

[EXPERIMENTAL] List your Slack reminders (pending and completed). Slack's reminders API has been partially deprecated since 2023 ("Save it for Later"). May become unreliable or stop working. Returns each reminder's id — pass it to complete_slack_reminder or delete_slack_reminder to manage one.

List active (non-bot, non-deleted) users in the Slack workspace. When name filter is provided, auto-paginates across up to 5 pages to find matches. For exact email match, prefer lookup_user_by_email.

Check Slack connection status. Call FIRST before any Slack operation. Returns: - connected: true/false - workspaces: array of connected workspaces with team names - tokenHealth: bot/user token status (valid|missing|refreshable|expired) CRITICAL: If response shows connected=false, call authenticate_slack_workspace to start the connection flow. The host will guide the user through OAuth.

Find a Slack user by their email address. PREFERRED method for resolving users — exact match, no ambiguity. WHEN TO USE: Always use this tool (instead of list_slack_users name search) when you have the user's email. It returns an exact match. WORKFLOW for sending DMs: 1. lookup_user_by_email({ email: "alice@company.com" }) → get user.id 2. open_slack_dm({ user: "<user_id>" }) → get DM channel 3. post_slack_message({ channel: "<dm_channel>", text: "...", intended_recipient: "<user_id>" }) Requires users:read.email scope (may need admin approval).

Mark messages in a channel as read up to a specific timestamp. Updates YOUR read position, not the bot's. Pass the ts of the last message you've read. For private channels/DMs, set include_private=true.

Open or get the DM channel with a user by their Slack User ID. REQUIRES a Slack User ID (U... or W...) — does NOT accept names or usernames. Use lookup_user_by_email (preferred, exact match) or list_slack_users to get the User ID first. Returns the DM channel ID (D...) plus verified recipient identity for use with post_slack_message. Does NOT send a notification. WORKFLOW: 1. lookup_user_by_email({ email: "alice@company.com" }) → get user.id 2. open_slack_dm({ user: "U1234567890" }) → get DM channel + verified recipient 3. post_slack_message({ channel: "D...", text: "...", intended_re…

Pin a message in a Slack channel so it appears in the channel's pinned items. Get the message timestamp from get_slack_channel_history (use the ts_slack value).

Post a message to a Slack channel as yourself. DM SAFETY: For direct messages (D... channels), intended_recipient (the recipient User ID) is REQUIRED. Without it the message is NOT sent — a DM has no visible recipient name, so sending unverified risks reaching the wrong person. The tool also refuses to send if intended_recipient does not match the actual DM recipient. To get a User ID use lookup_user_by_email, then open_slack_dm for their DM channel. PARAMETERS: channel, text, intended_recipient. Do not use channel_id or message — these are not the parameter names. Posted as the user — mess…

Remove your emoji reaction from a Slack message. Only removes the connected user's own reaction — other people's reactions on the same message are unaffected. Use list_slack_emoji to discover custom emoji names.

Reply to an existing message thread in Slack as yourself. PARAMETERS: channel, thread_ts, text. The thread_ts comes from ts_slack / thread_ts_slack on a message returned by get_slack_channel_history.

Schedule a message to be posted at a future time. post_at is a Unix timestamp in SECONDS (not ms). Max 30 scheduled messages per channel per 5 minutes. Max 120 days in advance.

Search messages across all channels in the Slack workspace. Requires user authorization. Uses Slack's Real-Time Search API (assistant.search.context) when the connected app has the granular search:read.* scopes; otherwise falls back to legacy search.messages, whose results are equally complete. The search_backend field records which one ran; it is diagnostic only. Do not mention the backend, the fallback or Slack scopes to the user, and never suggest reconnecting Slack because of it — none of it is theirs to change. Supports Slack search modifiers: - from:@username — Messages from a specifi…

Send yourself a Slack note that actually notifies you. This sends a direct message from the Slack app to you, so Slack treats it as a real notification. It is separate from your own self-DM "notes to self" space — same idea, different conversation, fewer mysteriously silent messages. PARAMETER: text. Use text, not message, note, or channel.

Remove a message from a Slack channel's pinned items. The message itself is NOT deleted — it is only removed from pinned items. Get the message timestamp from list_slack_pins or get_slack_channel_history (use the ts_slack value).

Edit a message you posted in Slack. Get the message timestamp from get_slack_channel_history (use the ts_slack value). Only your own messages can be edited (workspace admins may edit others').

Upload a local file to Slack (and optionally share it to a channel). Uses Slack's 3-step external upload flow (files.getUploadURLExternal → POST bytes → files.completeUploadExternal); the legacy files.upload endpoint was sunset by Slack in November 2025. WORKSPACE CONSTRAINT (security invariant): file_path must resolve inside the host's workspace directory (MCP_WORKSPACE_PATH, or the system temp dir when unset). Paths outside it — including symlinks pointing outside — are refused. Max file size: 50MB.