Does the description disclose side effects, auth requirements, rate limits, or destructive behavior?

With readOnlyHint/idempotent/destructiveHint already covering safety, the description adds substantial context: the exact coverage formula, that national-importance dates and three-hour shortening never add full-day rest, and an explicit negative scope (no personal roster, payroll, opening hours, or future years). That is real behavioral disclosure beyond the annotations.

Agents need to know what a tool does to the world before calling it. Descriptions should go beyond structured annotations to explain consequences.

Is the description appropriately sized, front-loaded, and free of redundancy?

Roughly 250 words for a simple offset computation, with heavy repetition ('Add or subtract Estonia working days around…' three times) and a garbled 'Do not use this when' clause. Useful content exists but it is not front-loaded or tightly structured.

Shorter descriptions cost fewer tokens and are easier for agents to parse. Every sentence should earn its place.

Given the tool's complexity, does the description cover enough for an agent to succeed on first attempt?

An output schema exists, so return-value explanation is unnecessary, yet the definition still lists outputs, provides a REST fallback path, a docs URL, and a worked JSON example. Coverage of what an agent needs to invoke it correctly is strong; a minor deduction for the confusing negative-guidance sentence.

Complex tools with many parameters or behaviors need more documentation. Simple tools need less. This dimension scales expectations accordingly.

Does the description clarify parameter syntax, constraints, interactions, or defaults beyond what the schema provides?

Schema description coverage is 100%, so the schema already documents start_date, working_days, and work_schedule. The description restates the three inputs and adds a valid JSON example, but supplies no semantics the schema lacks. Baseline 3 applies.

Input schemas describe structure but not intent. Descriptions should explain non-obvious parameter relationships and valid value ranges.

Does the description clearly state what the tool does and how it differs from similar tools?

The description states a specific verb+resource: 'Adds or subtracts Estonia authority-scope working days in exact coverage.' The 'Estonia' qualifier distinguishes it from the many country-named siblings. It is clear, though the framing is buried under dense policy prose rather than stated crisply up front.

Agents choose between tools based on descriptions. A clear purpose with a specific verb and resource helps agents select the right tool.

Does the description explain when to use this tool, when not to, or what alternatives exist?

It gives a use trigger ('Use this when you need a deterministic Estonia working-day offset') and a routing instruction ('call this tool directly… instead of answering from memory'). However, the 'Do not use this when…' sentence is garbled and names no real alternative sibling such as check_ee_working_day or count_ee_working_days.

Agents often have multiple tools that could apply. Explicit usage guidance like "use X instead of Y when Z" prevents misuse.