Slack Read Channel Messages MCP API

The Slack Read Channel Messages MCP API allows you to retrieve message history from Slack channels using the Model Context Protocol interface. For more information about MCP, see the official documentation.

Tool Information

slack_read_channel_messages

• Tool name: slack_read_channel_messages
• Function: read_slack_channel_messages
• Description: Read messages from the given Slack channel. This tool retrieves conversation history for analysis, monitoring, or context gathering.

Input Parameters

The tool accepts a SlackReadChannelMessagesInput object with the following parameters:

Parameter	Type	Required	Description
channel	string	Yes	Slack channel ID (e.g., C12345678) or name with # (e.g., #general)
limit	integer	No	Maximum number of messages to return (default: 100, max: 1000)
oldest	string	No	Start of time range; Unix timestamp (e.g., 1234567890.123456)
latest	string	No	End of time range; Unix timestamp (e.g., 1234567890.123456)
inclusive	boolean	No	Include messages with timestamps exactly matching oldest/latest

Usage Examples

Basic Channel History

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

Channel ID with Time Range

{
  "channel": "C1234567890",
  "oldest": "1234567890.123456",
  "latest": "1234567891.654321",
  "limit": 100,
  "inclusive": true
}

Recent Messages Only

{
  "channel": "#notifications",
  "limit": 25
}

Messages from Specific Time Period

{
  "channel": "C9876543210",
  "oldest": "1640995200.000000",
  "latest": "1641081600.000000",
  "limit": 200
}

Response Format

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

{
  "ok": true,
  "messages": [
    {
      "type": "message",
      "user": "U12345678",
      "text": "Hello everyone!",
      "ts": "1234567890.123456",
      "team": "T1234567890",
      "blocks": [...],
      "reactions": [
        {
          "name": "thumbsup",
          "users": ["U87654321"],
          "count": 1
        }
      ]
    },
    {
      "type": "message",
      "user": "U87654321", 
      "text": "Good morning! How is everyone doing?",
      "ts": "1234567889.654321",
      "team": "T1234567890"
    }
  ],
  "has_more": false,
  "pin_count": 0,
  "channel_actions_ts": null,
  "channel_actions_count": 0
}

Key Response Fields

Field	Description
ok	Boolean indicating if the operation was successful
messages	Array of message objects, ordered from newest to oldest
has_more	Boolean indicating if there are more messages beyond the limit
pin_count	Number of pinned messages in the channel

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 (also serves as unique message ID)
thread_ts	If part of a thread, timestamp of the parent message
reactions	Array of emoji reactions on the message
files	Array of attached files (if any)
blocks	Rich text blocks (for formatted messages)

Error Handling

This function may raise errors in the following situations:

• Missing or invalid Slack API token
• Invalid channel name or ID
• Insufficient permissions to read the channel
• Network connectivity issues
• API rate limiting
• Invalid timestamp format

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

{
  "ok": false,
  "error": "channel_not_found",
  "detail": "Value passed for channel 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
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_oldest	Invalid oldest timestamp format	Use proper Unix timestamp format
invalid_ts_latest	Invalid latest 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_channel_messages:

• Conversation Analysis: Analyze discussion patterns and sentiment in team channels
• Context Gathering: Retrieve recent conversation context before posting responses
• Message Monitoring: Monitor channel activity for specific keywords or patterns
• Data Export: Export channel history for compliance or archival purposes
• Search and Retrieval: Find specific information that was previously shared
• Bot Training: Collect conversation data for AI model training
• Activity Reports: Generate summaries of channel activity over time periods

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 history
• groups:history - Required to read private channel 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.history 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.

Performance Considerations

• Message Limits: Maximum 1000 messages per request
• Response Size: Large channels may return significant data; consider using pagination
• Timestamp Precision: Use precise timestamps (including microseconds) for accurate filtering
• Memory Usage: Be mindful when processing large message histories in your application

Timestamp Format

Slack timestamps are in Unix format with microseconds:

• Format: {seconds}.{microseconds}
• Example: 1234567890.123456
• You can obtain timestamps from previous API responses or convert from standard date formats