Server has 3 tools with schemas and descriptions present. Tool names follow verb_noun convention (set_list_*, set_smart_list_*). All descriptions are substantive (100-200+ chars) and explain state-mutation intent clearly. Input schemas are present with typed properties and descriptions. However, there are significant gaps: (1) no documented output schemas, callers don't know what these tools return, forcing LLMs to guess; (2) error handling descriptions are absent, tools don't guide recovery on failure; (3) parameter descriptions lack format/constraint details (e.g., 'UUID' is stated but no validation guidance for malformed input); (4) no idempotency guarantees stated despite state mutations; (5) resource interdependencies (list_id vs group behavior) are documented in set_list_appearance but not consistently across all tools. The tool names are clear and distinct, but descriptions could be more concise (set_list_appearance is 445 chars; pattern baseline is 194 chars p50). Overall, definitions are above-average in clarity but below production standards for error handling and output documentation.

• Document output schema for each tool. Example: 'Returns {"success": boolean, "list_id": string, "updated_at": ISO8601 timestamp}'. Even if response is minimal, schema sets expectations for the LLM.
• Add error handling section to each description. Example: 'Returns error 404 if list_id is invalid, try list_reminders_lists() to find valid IDs. Returns error 403 if user lacks permission to modify this list.'
• For set_list_appearance 'color' param, enumerate valid named tokens: 'Named color token (red, orange, yellow, green, blue, purple, brown, gray, ...) or #RRGGBB hex. Use reminders://appearance to discover available tokens.'
• For all params accepting IDs (list_id, smart_list_id), explain how to obtain them: 'UUID of the list. Call list_reminders_lists() first to retrieve available list UUIDs.'
• Add idempotency note to descriptions: 'Calling this tool multiple times with identical parameters is safe, subsequent calls will not create duplicates or produce side effects beyond the first call.'
• Reduce set_list_appearance description from 445 to ~180 chars by moving emblem catalog reference to parameter description of 'symbol' field.
• For set_list_appearance, clarify the group vs. list distinction with a concrete example: 'Groups only support name changes. Passing color, symbol, or emoji for a group returns error, validation happens server-side.'
• Validate parameter constraints early and return actionable error messages. Example: 'Invalid color: got "#GGGGGG". Must be a named token (red, blue, ...) or valid hex (#RRGGBB).'