Slack Automation

# 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_CONNECTIONS` with toolkit `slack`

- Always call `RUBE_SEARCH_TOOLS` first 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.

1. Verify Rube MCP is available by confirming `RUBE_SEARCH_TOOLS` responds

2. Call `RUBE_MANAGE_CONNECTIONS` with toolkit `slack`

3. If connection is not ACTIVE, follow the returned auth link to complete Slack OAuth

4. 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**:

1. `SLACK_FIND_CHANNELS` - Resolve channel name to channel ID [Prerequisite]

2. `SLACK_LIST_ALL_CHANNELS` - Fallback if FIND_CHANNELS returns empty/ambiguous results [Fallback]

3. `SLACK_FIND_USERS` - Resolve user for DMs or @mentions [Optional]

4. `SLACK_OPEN_DM` - Open/reuse a DM channel if messaging a user directly [Optional]

5. `SLACK_SEND_MESSAGE` - Post the message with resolved channel ID [Required]

6. `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 thread

- `blocks`: Block Kit layout blocks (deprecated, use markdown_text)

**Pitfalls**:

- `SLACK_FIND_CHANNELS` requires `query` param; missing it errors with "Invalid request data provided"

- `SLACK_SEND_MESSAGE` requires 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_ts` is omitted

- Persist `response.data.channel` and `response.data.message.ts` from 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**:

1. `SLACK_FIND_CHANNELS` - Resolve channel for scoped search with `in:#channel` [Optional]

2. `SLACK_FIND_USERS` - Resolve user for author filter with `from:@user` [Optional]

3. `SLACK_SEARCH_MESSAGES` - Run keyword search across accessible conversations [Required]

4. `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=true

- `sort`: 'score' (relevance) or 'timestamp' (chronological)

- `sort_dir`: 'asc' or 'desc'

**Pitfalls**:

- Validation fails if `query` is missing/empty

- `ok=true` can still mean no hits (`response.data.messages.total=0`)

- Matches are under `response.data.messages.matches` (sometimes also `response.data_preview.messages.matches`)

- `match.text` may be empty/truncated; key info can appear in `matches[].attachments[]`

- Thread expansion via FETCH_MESSAGE_THREAD can truncate when `response.data.has_more=true`; paginate via `response_metadata.next_cursor`

3. Manage Channels and Users

**When to use**: User wants to list channels, users, or workspace info

**Tool sequence**:

1. `SLACK_FETCH_TEAM_INFO` - Validate connectivity and get workspace identity [Required]

2. `SLACK_LIST_ALL_CHANNELS` - Enumerate public channels [Required]

3. `SLACK_LIST_CONVERSATIONS` - Include private channels and DMs [Optional]

4. `SLACK_LIST_ALL_U