Single tool with clear naming (analyze_bazi) and complete input schema. Description is adequate (194 chars, within baseline 34-392 range) and explains the domain well. All 5 parameters have type definitions and descriptions. However, output schema is not formally documented, only inferred from the text response. No error handling guidance, no parameter constraints beyond enums for gender, and no recovery hints for invalid dates. The tool is read-only and domain-specific, which limits composition concerns but also limits reusability.

• Add formal output schema to the tool definition: document that the response includes fields like year, month, day, hour (each with stem/branch), dayMaster, and dominantSoul. Use a structured JSON response instead of plain text to enable LLM field extraction.
• Add input validation with clear error messages. E.g., 'Invalid month: got 13, must be 1 - 12' or 'Invalid day for February: got 30, max is 28 (or 29 in leap years)'. Return actionable errors, not stack traces.
• Constrain numeric parameters in the schema: add 'minimum' and 'maximum' for year (e.g., 1900 - 2100), day (1 - 31, with note about month-specific limits), and hour (0 - 23). Document these in parameter descriptions.
• Clarify gender parameter behavior: update description to 'Optional; if omitted, defaults to [value]' so LLMs know what to expect when the parameter is not provided.
• Consider adding a 'timezone' parameter if birth time interpretation depends on local timezone. Currently, hour is assumed to be local time, document this assumption or accept timezone input.