The slackcli MCP server demonstrates solid definition quality with consistent naming patterns, complete parameter descriptions, and explicit schema definitions across all 23 tools. All tools follow verb_noun naming conventions (list_*, get_*, create_*, send_*, etc.). Tool descriptions are present and actionable, ranging from 26-95 characters. Input schemas use proper JSON Schema with typed parameters and descriptions. However, output schemas are not documented in the tool definitions themselves, responses are returned as JSON text without explicit type declarations. This is a moderate gap per the production baseline (100% of A+ tools have documented return types). Error handling exists but lacks granular recovery guidance (pattern:recovery-guide). No tool annotations (readOnlyHint/destructiveHint/idempotentHint) are visible despite the Risk column indicating semantic intent. The server correctly avoids exposing secrets as parameters (using environment-injected Slack API tokens).

• Document return type schemas for all tools. For each tool, add a response schema declaration (e.g., 'Returns a JSON object with fields: user_id (string), user (string), team_id (string), team (string), url (string)') or use OpenAPI-style response examples in the tool description.
• Add tool annotations: use mcp.WithToolHint(mcp.ReadOnlyHint) for all GET/LIST tools, mcp.WithToolHint(mcp.DestructiveHint) for delete_message and delete_file, mcp.WithToolHint(mcp.IdempotentHint) for read-only operations. This enables client-side confirmation dialogs and safety guardrails.
• Enhance error handling with recovery guidance. In error branches, return structured error objects (or append to result) that state: (1) what went wrong, (2) what the valid input should be, (3) a suggested next step (e.g., 'Call search_users() with a partial name').
• Document pagination response format explicitly. Update list_channels, list_users, list_messages, list_reactions, list_files descriptions to state: 'Returns an object with fields: items (array of <type>), next_cursor (string, null if end), total (number, if available)'.
• Implement optional confirmation for destructive operations. Add a dry-run parameter to delete_message and delete_file, or create separate confirm_delete_message / confirm_delete_file tools that preview the action.
• Support natural identifiers in lookup tools. Extend get_channel_info, get_user_info, etc. to accept both ID and name parameters (e.g., channel_id OR channel_name), resolving names to IDs internally.