Slack Read Thread Messages MCP API

The Slack Read Thread Messages MCP API allows you to retrieve messages from a specific thread in Slack channels using the Model Context Protocol interface. For more information about MCP, see the official documentation.

Tool Information

slack_read_thread_messages

• Tool name: slack_read_thread_messages
• Function: read_thread_messages
• Description: Read messages from a specific thread in a given Slack channel. This tool retrieves threaded conversation history for context analysis or follow-up actions.

Input Parameters

The tool accepts a SlackReadThreadMessagesInput object with the following parameters:

Parameter	Type	Required	Description
channel	string	Yes	Slack channel ID (e.g., C12345678) or name with # (e.g., #general)
thread_ts	string	Yes	Timestamp ID of the parent message that started the thread
limit	integer	No	Maximum number of messages to retrieve (default: 100)

Usage Examples

Basic Thread Reading

{
  "channel": "#general",
  "thread_ts": "1234567890.123456",
  "limit": 50
}

Channel ID with Thread

{
  "channel": "C1234567890",
  "thread_ts": "1234567890.123456"
}

Limited Thread Messages

{
  "channel": "#support-requests",
  "thread_ts": "1640995200.000000",
  "limit": 25
}

Recent Thread Activity

{
  "channel": "C9876543210",
  "thread_ts": "1641081600.123456",
  "limit": 10
}

Response Format

The tool returns the raw JSON response from Slack's conversations.replies API:

{
  "ok": true,
  "messages": [
    {
      "type": "message",
      "user": "U12345678",
      "text": "This is the original message that started the thread",
      "ts": "1234567890.123456",
      "team": "T1234567890",
      "thread_ts": "1234567890.123456",
      "reply_count": 3,
      "reply_users_count": 2,
      "latest_reply": "1234567892.789012",
      "reply_users": ["U87654321", "U11111111"]
    },
    {
      "type": "message",
      "user": "U87654321",
      "text": "This is a reply in the thread",
      "ts": "1234567891.456789",
      "team": "T1234567890",
      "thread_ts": "1234567890.123456",
      "parent_user_id": "U12345678"
    },
    {
      "type": "message",
      "user": "U11111111",
      "text": "Another reply with more details",
      "ts": "1234567892.789012",
      "team": "T1234567890",
      "thread_ts": "1234567890.123456",
      "parent_user_id": "U12345678",
      "reactions": [
        {
          "name": "eyes",
          "users": ["U12345678"],
          "count": 1
        }
      ]
    }
  ],
  "has_more": false,
  "response_metadata": {
    "next_cursor": ""
  }
}

Key Response Fields

Field	Description
ok	Boolean indicating if the operation was successful
messages	Array of message objects, including the parent message and all replies
has_more	Boolean indicating if there are more messages beyond the limit
response_metadata	Pagination metadata including next_cursor

Thread Message Object Fields

Field	Description
type	Message type (usually "message")
user	User ID of the message sender
text	The message text content
ts	Message timestamp (unique message ID)
thread_ts	Timestamp of the parent message (same for all messages in thread)
parent_user_id	User ID of the thread starter (only on replies, not parent)
reply_count	Number of replies in thread (only on parent message)
reply_users	Array of user IDs who have replied (only on parent message)
latest_reply	Timestamp of the most recent reply (only on parent message)

Error Handling

This function may raise errors in the following situations:

• Missing or invalid Slack API token
• Invalid channel name or ID
• Invalid thread timestamp
• Insufficient permissions to read the channel
• Thread doesn't exist
• Network connectivity issues
• API rate limiting

Error responses will have "ok": false and include an error message:

{
  "ok": false,
  "error": "thread_not_found",
  "detail": "Value passed for thread_ts was invalid."
}

Common Error Codes

Error Code	Description	Solution
channel_not_found	Channel doesn't exist or bot lacks access	Verify channel name/ID and bot permissions
thread_not_found	Thread timestamp is invalid or thread doesn't exist	Verify the thread_ts parameter
not_in_channel	Bot is not a member of the channel	Invite the bot to the channel
invalid_auth	Invalid or missing API token	Check SLACK_BOT_TOKEN environment variable
invalid_ts	Invalid thread timestamp format	Use proper Unix timestamp format
rate_limited	Too many requests sent	Implement rate limiting in your application

Use Cases

Typical scenarios for using slack_read_thread_messages:

• Thread Context Analysis: Understand the full context of a conversation thread
• Follow-up Actions: Retrieve thread history before adding new replies
• Support Ticket Tracking: Monitor resolution progress in support threads
• Meeting Notes: Extract discussion details from meeting-related threads
• Decision Tracking: Follow the evolution of decisions made in threads
• Knowledge Base: Extract Q&A patterns from help threads
• Conversation Summarization: Generate summaries of lengthy thread discussions

Authentication

This tool requires a valid Slack bot token set in one of the following environment variables:

• SLACK_BOT_TOKEN (recommended)
• SLACK_TOKEN (fallback)

The bot must have the following OAuth scopes:

• channels:history - Required to read public channel thread history
• groups:history - Required to read private channel thread history (if needed)
• channels:read - Required to access channel information
• groups:read - Required to access private channel information (if needed)

Rate Limiting

Slack enforces rate limits on the conversations.replies API:

• Tier 2: 20+ requests per minute
• Tier 3: 50+ requests per minute
• Tier 4: 100+ requests per minute

The server will automatically handle retries according to Slack's rate limiting headers.

Thread Behavior Notes

• Parent Message: The first message in the response is always the original message that started the thread
• Chronological Order: Messages are returned in chronological order (oldest first)
• Thread Limits: Threads can have up to 1000 replies
• Pagination: Use limit parameter and next_cursor for large threads
• Thread Identification: All messages in a thread share the same thread_ts value

Best Practices

• Cache Thread Data: Store thread information to avoid repeated API calls
• Monitor Thread Updates: Use webhooks or periodic polling for active threads
• Handle Large Threads: Implement pagination for threads with many messages
• Preserve Context: Keep the parent message for context when processing replies
• Thread Completion: Check latest_reply timestamp to determine thread recency