The Slack MCP server has 8 tools with mixed definition quality. All tools have names starting with action verbs (search_, send_, list_, get_, read_, refresh_), which is positive. However, descriptions are inconsistent, some are bare minimal (read_thread: no description provided in handler), and parameter descriptions lack detail on formats, constraints, and expected values. Input schemas are visible for most tools but lack type validation details (e.g., no min/max for limit parameters, no enum constraints for channel parameter formats). Output schemas are not documented at all, forcing LLMs to guess what fields responses contain. Error handling guidance is minimal. The tool composition is reasonable (8 focused tools), but several tools mix concerns or lack sufficient context to be effective in agent workflows.

• Add a substantive description to read_thread (currently empty). Example: 'Read all messages in a Slack thread. Pass the channel ID and thread_ts from the parent message to fetch replies. Returns a list of message objects with author, text, and timestamp.'
• Document output schemas for all 8 tools. For search_users, specify: returns {users: [{user_id: string, name: string, email: string, avatar_url: string}], total_count: number}. For send_message: {message_ts: string, text: string, channel: string}.
• Enhance parameter descriptions with format and constraint details. Example: 'query (string, 1-255 chars): Search term for user names or emails. Supports partial matches. Case-insensitive.'
• Add min/max bounds to numeric parameters. E.g., 'limit (1-100, default 10): Maximum number of results to return.'
• Add state-mutation clarity to send_message: 'Sends a message to a Slack channel or DM. This is a permanent action, verify the channel and text before calling. Supports optional thread replies via thread_ts (string).'
• Document pagination response structure. E.g., for get_channel_messages: 'Returns {messages: [...], next_cursor: string|null, total_count: number}. Use next_cursor to fetch additional pages.'
• Add error recovery hints in descriptions. E.g., 'If user not found, try search_users() with a partial name or email domain.'
• Specify what IDs downstream tools need. Document that send_message returns message_ts which read_thread requires, and that search_messages returns channel IDs that get_channel_messages and list_channel_members accept.

Inferred effective spec: <=2025-11-25.

• Relies on Logging (deprecated) - log to stderr or use OpenTelemetry