Single tool 'add' has critical definition gaps. Input schema present with Zod types (a, b as numbers) but parameter descriptions are null, violating the requirement that every parameter needs a description. Tool description is missing entirely (no docstring visible in registration). Output schema not documented. No error handling guidance. Naming is generic and doesn't follow verb_noun convention (should be 'sum_numbers' or 'calculate_sum'). This server fails multiple hard scoring rules.

• Add a tool description: 'Adds two numbers and returns their sum. Use this when the user asks for arithmetic addition.'
• Add descriptions to parameters: a='First number to add (numeric)', b='Second number to add (numeric)'
• Document the output schema: 'Returns an object with a single text field containing the numeric result as a string.'
• Rename tool from 'add' to 'sum_numbers' to follow verb_noun convention and improve LLM discoverability.
• Implement input validation with actionable error messages: 'Invalid input: a and b must be numbers. Got a={type(a).__name__}, b={type(b).__name__}'