Strong foundation with 21 well-structured tools, comprehensive schemas, and consistent descriptions. All tools have explicit input schemas with type definitions and descriptions. Tool annotations (readOnlyHint, destructiveHint, idempotentHint) are correctly applied. Write operations include authorization gates and backup mechanisms. Main gaps: parameter descriptions are sometimes generic (e.g., 'Kimai entity ID' lacks format/range guidance); some enum parameters lack inline constraint documentation; output schemas are not formally documented in code; error recovery guidance is minimal.

• Add min/max constraints to all numeric parameters in schema definitions. E.g., page: {type: 'number', minimum: 1, maximum: 999999}, size: {type: 'number', minimum: 1, maximum: 500}. Include these in parameter descriptions: 'Page number (1 - 999999).'
• Document output schemas for each tool. Add a 'returns' section to tool descriptions or create a separate schema map. E.g., 'Returns: {items: [{id, name, email}], page, total, count}' so LLMs know what fields are available for chaining.
• Enhance error messages with recovery hints. In formatApiError(), detect error type and append guidance: 'Customer not found. Try kimai_list_customers() to find the correct ID.' This guides agents toward self-correction.
• Clarify authorization gates in write-tool descriptions. Add: 'This tool requires explicit human authorization via authorization_confirmed=true and a reason in authorization_note. Without both, the request is rejected.' Make the gate non-negotiable in the description.
• Add examples to parameter descriptions for complex fields. E.g., 'begin timestamp in ISO 8601 format: 2026-06-01T09:00:00' (not as a default, but as a format hint). This helps LLMs construct valid inputs without trial-and-error.