Four read-only utility tools with clear, actionable descriptions (avg 156 chars). All tools have input schemas with typed parameters and descriptions. Naming is verb-forward (calculate, solve_equation, date_diff, date_add). However, schemas lack explicit output documentation, error handling guidance is absent, and parameter constraints (e.g., date format validation, expression syntax rules) are described informally rather than via JSON Schema patterns/enums. No tool annotations (readOnlyHint present but not declared). Composition is sound, each tool does one thing. Missing: recovery guidance for invalid inputs, pagination (not applicable here), and structured error responses.

• Add explicit output schema to each tool. E.g., calculate() returns {"result": number, "expression": string, "error": string|null}. Document in tool description.
• Replace informal format descriptions with JSON Schema patterns. date_diff/date_add: add 'pattern': '^\d{4}-\d{2}-\d{2}$' to date parameters.
• Add error handling examples to descriptions. E.g., 'If the equation has no real solutions, returns {"error": "No real solutions"}. Try solve_equation with a different equation.'
• Declare readOnlyHint: true in all four tool definitions to signal safety to LLMs and prevent unnecessary confirmation prompts.
• Expand calculate() description to list supported functions: 'Supports: +, -, *, /, **, %, //, sqrt(), sin(), cos(), log(), factorial(), and parentheses. Returns {"result": number, "expression": string}.'