Single tool 'add_two_numbers' has critical definition gaps. Tool name lacks action verb clarity (should be 'sum_numbers' or 'calculate_sum'). Description is minimal (12 chars, below 20-char threshold). Input parameters 'a' and 'b' have null descriptions, violates requirement that every parameter must have a non-empty description. No output schema documented. No error handling guidance. Zod schema present but parameter descriptions missing entirely in the tool registration.

• Add non-empty descriptions to parameters 'a' and 'b'. Example: 'a': {type: 'number', description: 'First number to add (any real number)'}
• Expand tool description to 50-150 chars. Example: 'Add two numbers together and return the sum. Accepts integers and decimals. Returns the numeric result as a string.'
• Rename tool to 'sum_numbers' or 'calculate_sum' for clearer action verb and intent signaling.
• Document output schema explicitly. Define that the tool returns {content: [{type: 'text', text: string}]} where text is the numeric sum.
• Add input validation and error handling. Return actionable errors like 'Invalid input: a and b must be numbers. Got a={value}, b={value}' instead of silent failures.