The server has 16 well-structured tools with explicit registration, input schemas, descriptions, and tool annotations (readOnlyHint, destructiveHint, idempotentHint). However, several critical gaps reduce overall quality: (1) Most parameter descriptions are minimal or generic (e.g., 'Amount of the transaction' lacks format/constraints); (2) Output schemas are NOT documented, the code returns JSON.stringify(response.data) with no typed response definition visible; (3) Error handling is basic (throwing generic Error objects) with no recovery guidance; (4) Several tools lack clarity on what data they return and how to chain results; (5) Some parameter names and schemas have inconsistencies (e.g., 'amount' has no type declaration visible in schema; 'transactionId' is described the same way across three different tools despite different contexts). Tools like getTransactions and createTransaction have reasonable schemas but descriptions could be more action-focused. The code quality is good (Zod validation, proper API calls), but the tool interface design lacks the LLM-optimization needed for production agent use.

• Add explicit TypeScript interfaces or JSON Schema definitions for the response object of each tool. For example, define getCategoriesByType as returning {categories: string[], count: number} and document this in the tool registration.
• Fix the 'amount' parameter in createRecurringTransaction, editRecurringTransaction, createTransaction, and editTransaction by adding type: 'number' and constraints like minimum: 0, multipleOf: 0.01 to the schema.
• Enhance error messages with recovery hints. Replace 'Invalid custom category input' with 'Invalid categories. Validation failed: [details]. Valid category names must be 1-50 characters. To add a category, call createCustomCategories() first.'
• Clarify the 'interval' and 'occurrence' relationship in createRecurringTransaction and editRecurringTransaction descriptions. Example: 'interval: number indicating the count (1-500); occurrence: enum (day|month|year) indicating the unit. interval=2 with occurrence=month means every 2 months.'
• Add distinct descriptions to markRecurringTransactionDone, skipRecurringTransaction, and deleteRecurringTransaction. Use terms like: Mark as 'done' (completed for this period, can resume next period); Skip (omit this period, resume next); Delete (permanent, irreversible removal).
• Add limit and offset parameters to getTransactions, getCategoriesByType, getCustomCategories, and getRecurringTransactions. Document default limits (e.g. 'Returns up to 50 results. Use offset and limit to paginate larger datasets.').
• Fix getTransactions 'paymentModes' parameter: change type from 'string' to 'array of strings' with items: {type: string, enum: [...]}, or rename to 'paymentMode' (singular) and document that only one mode can be filtered at a time.