
About
Automate Slack workspace operations including messaging, search, channel management, and reaction workflows through Composio's Slack toolkit.
name: slack-automation description: "Automate Slack workspace operations including messaging, search, channel management, and reaction workflows through Composio's Slack toolkit." risk: critical source: community date_added: "2026-02-27"
Slack Automation via Rube MCP
Automate Slack workspace operations including messaging, search, channel management, and reaction workflows through Composio's Slack toolkit.
Prerequisites
- Rube MCP must be connected (RUBE_SEARCH_TOOLS available)
- Active Slack connection via
RUBE_MANAGE_CONNECTIONSwith toolkitslack - Always call
RUBE_SEARCH_TOOLSfirst to get current tool schemas
Setup
Get Rube MCP: Add https://rube.app/mcp as an MCP server in your client configuration. No API keys needed — just add the endpoint and it works.
- Verify Rube MCP is available by confirming
RUBE_SEARCH_TOOLSresponds - Call
RUBE_MANAGE_CONNECTIONSwith toolkitslack - If connection is not ACTIVE, follow the returned auth link to complete Slack OAuth
- Confirm connection status shows ACTIVE before running any workflows
Core Workflows
1. Send Messages to Channels
When to use: User wants to post a message to a Slack channel or DM
Tool sequence:
SLACK_FIND_CHANNELS- Resolve channel name to channel ID [Prerequisite]SLACK_LIST_ALL_CHANNELS- Fallback if FIND_CHANNELS returns empty/ambiguous results [Fallback]SLACK_FIND_USERS- Resolve user for DMs or @mentions [Optional]SLACK_OPEN_DM- Open/reuse a DM channel if messaging a user directly [Optional]SLACK_SEND_MESSAGE- Post the message with resolved channel ID [Required]SLACK_UPDATES_A_SLACK_MESSAGE- Edit the posted message if corrections needed [Optional]
Key parameters:
channel: Channel ID or name (without '#' prefix)markdown_text: Preferred field for formatted messages (supports headers, bold, italic, code blocks)text: Raw text fallback (deprecated in favor of markdown_text)thread_ts: Timestamp of parent message to reply in a threadblocks: Block Kit layout blocks (deprecated, use markdown_text)
Pitfalls:
SLACK_FIND_CHANNELSrequiresqueryparam; missing it errors with "Invalid request data provided"SLACK_SEND_MESSAGErequires valid channel plus one of markdown_text/text/blocks/attachments- Invalid block payloads return error=invalid_blocks (max 50 blocks)
- Replies become top-level posts if
thread_tsis omitted - Persist
response.data.channelandresponse.data.message.tsfrom SEND_MESSAGE for edit/thread operations
2. Search Messages and Conversations
When to use: User wants to find specific messages across the workspace
Tool sequence:
SLACK_FIND_CHANNELS- Resolve channel for scoped search within:#channel[Optional]SLACK_FIND_USERS- Resolve user for author filter withfrom:@user[Optional]SLACK_SEARCH_MESSAGES- Run keyword search across accessible conversations [Required]SLACK_FETCH_MESSAGE_THREAD_FROM_A_CONVERSATION- Expand threads for relevant hits [Required]
Key parameters:
query: Search string supporting modifiers (in:#channel,from:@user,before:YYYY-MM-DD,after:YYYY-MM-DD,has:link,has:file)count: Results per page (max 100), or total with auto_paginate=truesort: 'score' (relevance) or 'timestamp' (chronological)sort_dir: 'asc' or 'desc'
Pitfalls:
- Validation fails if
queryis missing/empty ok=truecan still mean no hits (response.data.messages.total=0)- Matches are under
response.data.messages.matches(sometimes alsoresponse.data_preview.messages.matches) match.textmay be empty/truncated; key info can appear inmatches[].attachments[]- Thread expansion via FETCH_MESSAGE_THREAD can truncate when
response.data.has_more=true; paginate viaresponse_metadata.next_cursor
3. Manage Channels and Users
When to use: User wants to list channels, users, or workspace info
Tool sequence:
SLACK_FETCH_TEAM_INFO- Validate connectivity and get workspace identity [Required]SLACK_LIST_ALL_CHANNELS- Enumerate public channels [Required]SLACK_LIST_CONVERSATIONS- Include private channels and DMs [Optional]SLACK_LIST_ALL_USERS- List workspace members [Required]SLACK_RETRIEVE_CONVERSATION_INFORMATION- Get detailed channel metadata [Optional]SLACK_LIST_USER_GROUPS_FOR_TEAM_WITH_OPTIONS- List user groups [Optional]
Key parameters:
cursor: Pagination cursor fromresponse_metadata.next_cursorlimit: Results per page (default varies; set explicitly for large workspaces)types: Channel types filter ('public_channel', 'private_channel', 'im', 'mpim')
Pitfalls:
- Workspace metadata is nested under
response.data.team, not top-level SLACK_LIST_ALL_CHANNELSreturns public channels only; useSLACK_LIST_CONVERSATIONSfor private/IM coverageSLACK_LIST_ALL_USERScan hit HTTP 429 rate limits; honor Retry-After header- Always
Compatible Tools
Claude CodeCursor
Tags
Backend
