This server has well-defined tools with proper JSON schemas and clear descriptions. All 11 tools are explicitly registered with input schemas in Tools.ts. Naming follows verb_noun patterns consistently (slack_list_*, slack_get_*, slack_post_*, slack_reply_*, slack_add_*). However, there are notable gaps: output schemas are not documented, error handling is absent from visible code, and some parameter descriptions lack detail about constraints and format expectations. The descriptions are generally adequate (averaging ~80-120 chars) but several lack guidance on when/why to use the tool or prerequisites. No tool annotations (readOnlyHint/destructiveHint) are visible. Parameter designs are reasonable but could be improved: some tools accept ambiguous dual parameters (e.g., slack_post_message accepts channel_name OR channel_id without documenting mutual exclusivity clearly), and formats like thread_ts lack strict validation guidance despite complex formatting rules. Overall, the server is functionally sound but falls short of production-grade polish.

• Document return types for all tools. Add a 'Returns' section to each tool description or a separate schema file. Example for slack_list_channels: 'Returns object with keys: channels (array of {id, name, is_archived, created}), response_metadata (pagination info), and next_cursor if more results exist.'
• Add explicit 'mutually exclusive' guidance to slack_post_message and slack_get_dm_history descriptions: 'Provide channel_id OR channel_name, not both. If both provided, channel_id takes precedence.'
• Rewrite thread_ts parameter descriptions with a concrete regex or format example: 'Unix timestamp with 6-digit microsecond suffix (e.g., 1609459200.123456). To convert a timestamp like 1609459200 to this format, append .000000'
• Implement structured error responses with classifications. Return objects like {error: 'user_not_found', recovery: 'Try slack_get_users() to search for the user first', retryable: false}
• Add tool annotation hints to InputSchema. For write tools, add 'destructiveHint: true'. For read-only tools, add 'readOnlyHint: true'. This enables client UI and agent safety guardrails.
• Convert parameter constraints from descriptions to JSON Schema. Use 'minimum': 1, 'maximum': 200 for numeric bounds instead of relying on description text.
• Clarify slack_post_message behavior when channel is omitted. Either make channel_id or channel_name required (via 'oneOf' schema pattern), or explicitly document fallback behavior.
• Add pagination best-practice guidance: 'If response includes next_cursor (not null), more results exist. Pass that cursor to the next call to fetch the next page.'

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

• Relies on Stateful initialize / Mcp-Session-Id (removed; protocol is stateless) - make each request self-contained