Two tools with basic schemas and minimal descriptions. Both tools have input schemas with proper types (number, enum), but descriptions are extremely short (10-40 chars) and lack context for LLM selection. No output schema documentation. No error handling guidance beyond a single divide-by-zero check. Tool names are verb-based but generic. Schemas present but descriptions fall well below the 50-200 char baseline for A+ tools.

• Expand 'add' description to: 'Adds two numbers and returns the sum. Use when you need basic arithmetic addition. Returns a single numeric result.'
• Expand 'calculate' description to: 'Performs arithmetic operations (add, subtract, multiply, divide) on two numbers. Specify the operation and operands. Returns the numeric result or an error if division by zero is attempted.'
• Document output schema: both tools return {type: 'text', text: string} containing a numeric result or error message. Specify that results are returned as strings.
• Add input validation: reject non-numeric inputs with actionable errors like 'Invalid input: a must be a number, got "abc"'.
• Rename tools to reduce ambiguity: 'add_numbers' and 'perform_arithmetic' or 'calculate_arithmetic'.