Three well-designed read-only tools with clear naming, solid descriptions (150-200 chars each), and complete input schemas. All parameters are typed and described. Error handling is thoughtful, ToolError exceptions surface readable messages to the LLM, not tracebacks. Results are capped at MAX_ROWS=100 with truncation warnings. Output is formatted as readable text rather than structured JSON, which is appropriate for a read-only analytics server but limits downstream tool chaining. No tool annotations (readOnlyHint, etc.) present. Overall strong for a focused domain tool, but lacks some production patterns around output structure and composition.

• Return structured JSON objects instead of formatted text. E.g., find_customer should return {customers: [{id, name, email, company, plan, country, signed_up_on, order_count, lifetime_value}], total_matched: N}. This enables downstream tool chaining and reduces LLM parsing errors.
• Add tool annotations to all three tools: readOnlyHint=true and idempotentHint=true. This signals to LLMs that these tools are safe to retry and do not modify state.
• Document output schemas in tool docstrings. E.g., 'Returns: {customers: [{id: int, name: str, email: str, company: str, plan: str, country: str, signed_up_on: str, order_count: int, lifetime_value: float}], total_matched: int}'.
• Declare revenue_summary's group_by parameter as an enum constraint in the schema: enum=['month', 'plan', 'product', 'country', 'customer']. Remove the free-form string validation.
• Add format='date' constraint to start_date and end_date parameters in list_orders and revenue_summary. This signals to LLMs that ISO 8601 format is required.

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

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