The server demonstrates solid fundamentals with 12 well-named, verb-leading tools covering a real accounting domain. All tools have non-empty descriptions (10-200 chars range, mostly in the good 50-150 char zone). Input schemas are visible and structured with zod validation. However, critical gaps reduce confidence: (1) Output schemas are NOT documented in tool definitions, only internal TypeScript interfaces exist, forcing LLMs to infer structure. The rubric requires 'Document the output schema' (pattern:tool). (2) Parameter descriptions lack depth, most are 1-2 sentences; none explain format, range, constraints, or dependencies. E.g., 'amount' has no min/max, 'dateFrom'/'dateTo' mention 'natural language' but no examples of what's accepted. (3) Error handling is invisible in the provided code, no recovery guidance, no classification of retryable vs fatal errors. (4) No evidence of idempotency, confirmation steps, or dry-run modes for destructive operations (banking_create_transfer, create_invoice, create_expense, send_invoice). A production tool transferring $25k should have a confirmation pattern. (5) Tool composition is good (each does one thing), but no evidence of response field naming consistency across related tools (e.g., does get_invoices return 'invoice_id' or 'id'?). Per-tool quality is 60-75; averaging ~68.

• Document output schemas explicitly in each tool definition. Use JSON Schema for return types and include sample response structures. Example: 'Returns object with fields: {id: string, name: string, balance: number (formatted as currency string)}'.
• Add min/max constraints to all numeric parameters. E.g., 'amount' (required, type: number, minimum: 0.01, maximum: 999999999), 'limit' (type: number, minimum: 1, maximum: 100, default: 20).
• Convert all enum-like parameters to formal JSON Schema enums. E.g., for bill_get_bills 'status', use 'enum: ["unpaid", "paid", "overdue", "all"]' instead of relying on description examples.
• Add error handling and recovery guidance to tool descriptions. E.g., 'If transfer fails due to insufficient balance, call get_account_balance first to verify funds. If vendor not found during expense creation, call get_vendors to discover valid vendor names.'
• Implement confirmation/dry-run patterns for destructive operations. Add optional 'dryRun: boolean' parameter to banking_create_transfer, create_invoice, create_expense, send_invoice. Return expected outcome without side effects when dryRun=true.
• Standardize date parameter format descriptions. Define a canonical format (ISO 8601 with examples: '2024-01-15') and state whether natural-language dates are supported (e.g., 'Supports natural language like "this month", "last 30 days", or ISO 8601 format "2024-01-15"').
• Add pagination support to list operations. Include 'offset' (default: 0) and 'limit' (default: 20, max: 100) parameters. Return 'total_count' and 'has_more' in responses to enable paginated iteration.

Inferred effective spec: <=2025-11-25.

• Relies on Logging (deprecated) - log to stderr or use OpenTelemetry