Single tool 'get_stock_info' has a complete JSON Schema with all required parameters typed and described. However, the tool description is in Japanese and lacks clarity on when to use it vs alternatives. Parameter descriptions are present but generic (e.g., '証券コード' without format guidance). No output schema is documented, the tool returns raw JSON from yfinance without specifying field structure, making it hard for LLMs to extract data reliably. Error handling exists but lacks recovery guidance. The tool does one thing (fetch stock data) but composition is minimal with only one tool available.

• Add English description: 'Fetch historical stock price data (OHLCV) for a given ticker symbol. Use this to analyze price trends, volatility, or support/resistance levels. Returns daily/intraday data indexed by timestamp.'
• Document output schema: 'Returns JSON object with date keys (ISO 8601) and values containing {Open, High, Low, Close, Volume} fields. Example: {"2024-01-15T00:00:00": {"Open": 150.5, "High": 152.3, ...}}'
• Convert period and interval descriptions to JSON Schema enums instead of free-form examples: period: enum ["1d", "5d", "1mo", "3mo", "6mo", "1y", "2y", "5y", "10y", "ytd", "max"]
• Enhance error messages with recovery hints: 'Ticker "INVALID" not found. Check ticker format (e.g., AAPL for US stocks, 7203.T for Japan). Try search_tickers() to find valid symbols.' (if search tool existed)
• Add result limiting: 'Returns up to 10,000 data points. For large date ranges, use smaller intervals or split into multiple requests with start_date/end_date.'

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

• Relies on Logging (deprecated) - log to stderr or use OpenTelemetry