The server exposes three weather lookup tools with clear verb-based names (get_weather, get_available_prefectures, get_available_cities). All three tools are explicitly registered in FastMCP and have descriptions. However, there are significant gaps in schema documentation and parameter descriptions. The input schemas are visible and typed, but parameter descriptions are minimal or missing context for LLM reasoning. Output schemas are not documented at all. Error handling is minimal, no guidance on what happens when a prefecture or city is not found, no recovery suggestions. The tool names are appropriate but descriptions lack the depth needed to help an LLM decide WHEN to use each tool versus others. The server is READ_ONLY with no state modifications, reducing risk, but the lack of comprehensive documentation and error guidance keeps the overall score in the fair-to-poor range.

• Document output schemas for all three tools. Include sample responses showing the structure of weather data (e.g., {temperature: number, conditions: string, forecast: [{date: string, high: number, low: number}]}), available prefectures (array of strings or objects), and available cities (array of strings or objects with prefecture mapping).
• Expand parameter descriptions to explain context and valid formats. Example: 'prefecture: Prefecture name in Japan (English romanization, e.g., 'Tokyo', 'Hokkaido'). Call get_available_prefectures() to see all valid options.' and 'city: City name in English or Japanese. Optional; if omitted, returns forecast for the largest city in the prefecture. Call get_available_cities(prefecture) to discover city options.'
• Add error handling and recovery guidance to tool descriptions. Example: 'If the prefecture or city is not found, the tool will return an error with available alternatives. Call get_available_prefectures() or get_available_cities() to verify valid names.'
• Clarify the relationship between the three tools in each description. Example for get_weather: 'Retrieves current weather and forecast. Start with get_available_prefectures() to discover valid prefectures, then get_available_cities(prefecture) to choose a city.'
• Define the default city selection logic explicitly: 'If city is omitted, the tool returns data for the first city alphabetically in the prefecture_data list (e.g., Hokkaido defaults to Asahikawa).' Or document the actual ordering used.