Single-tool server with generally adequate schema and description, but lacks enterprise-grade error handling, output structure documentation, and pagination support. The tool definition is explicit and properly registered with Zod schema, but the implementation has critical gaps in error guidance and response structure. Tool naming follows verb_noun convention (get_ptna_news), which is good. Description is present at 108 characters, within acceptable range. However, the parameter descriptions are verbose (category param description is ~400 chars) and the output schema is undocumented, LLMs cannot predict return structure. Error handling returns generic messages ('ニュース取得中にエラーが発生しました') without actionable guidance or error classification.

• Document the output schema explicitly. Define return structure as: {content: [{type: 'text', text: string}], metadata: {total_count: number, returned_count: number, category_applied?: string}}. Or better: return {items: [{title, author, datetime, url, description}], total, category_used}.
• Convert category parameter to enum: z.enum(['コンペティション', '提携コンクール', 'コンサート', 'セミナー', '調査・研究', 'ステップ', '指導者ライセンス', '寄付・CrossGiving', 'コーポレート', '今週のコラム', 'OPEN PIANO PROJECT', '教室紹介']).optional().describe('...').
• Add pagination: accept offset and cursor parameters, return next_cursor if more results available. E.g., limit: z.number().min(1).max(50).default(10), offset: z.number().min(0).default(0).
• Improve error handling: distinguish between network errors ('Failed to fetch from piano.or.jp. Will retry.'), invalid category ('Invalid category. Try: コンペティション, コンサート, ...'), and timeout ('Request timed out after 5s. Try again.'). Include recovery hints.
• Fix filtering logic: use exact enum matching instead of substring includes(). Map category enum value to author field values via a lookup table.
• Add bounds validation to limit parameter: z.number().min(1).max(100).default(10). Return clear error if violated.
• Return structured JSON array of news items instead of concatenated text. Allows LLMs to iterate, filter, and format on the fly.
• Consider adding optional parameters: sort_by (date_desc/date_asc), date_range (e.g., last_7_days, last_30_days) to reduce large result sets without agent post-processing.