This server exhibits critical deficiencies across naming, descriptions, schemas, and error handling. Of 7 tools evaluated, 4 lack ANY description text, 3 have trivial or missing parameter documentation, and ALL tools lack output schema documentation. The server mixes two unrelated domains (expense management and calculator) without clear separation. Tool names lack action verbs (e.g., 'add' is ambiguous, does it mean addition or expense entry?). Parameter schemas exist but descriptions are minimal or absent. No evidence of error handling, validation guidance, or recovery strategies. This is a teaching/demo server that would not pass production review.

• Add non-empty descriptions (50-150 chars) to every tool. For find_expenses: 'Retrieve all expenses in the database. Returns an array of expense objects with id, description, amount, and date. Use to review spending history or audit expenses.' For divide: 'Divide num1 by num2. Returns the quotient as a decimal number. Returns an error if num2 is zero; in that case, choose a different denominator.'
• Document output schemas for all tools. Example for find_expenses: {type: 'object', properties: {expenses: {type: 'array', items: {type: 'object', properties: {id: {type: 'string'}, description: {type: 'string'}, amount: {type: 'number'}, date: {type: 'string', format: 'date-time'}}, required: ['id', 'description', 'amount', 'date']}, total: {type: 'integer'}}}}
• Rename calculator tools to verb_noun pattern: add → add_numbers, subtract → subtract_numbers, multiply → multiply_numbers, divide → divide_numbers. This eliminates naming conflicts with add_expense and clarifies intent.
• Add pagination to find_expenses: accept optional limit (default 20, max 100) and offset (default 0) parameters. Return {expenses: [...], total: <count>, limit, offset} to enable iteration without context explosion.
• Add error handling to divide: catch division by zero and return {error: 'Division by zero', numerator: <num1>, denominator: <num2>, suggestion: 'Try a different denominator.'}
• Add validation to add_expense: document that amount must be >= 0 (or specify if negative expenses are allowed). Clarify date format (ISO 8601 recommended). Return created expense object including the generated _id and timestamp.