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

Annotations already cover read-only/idempotent/non-destructive safety, but the description adds real behavioral context beyond them: the exact planning_workday formula, that memorial days and person-specific religious rights are not general rest, and a named REST fallback endpoint to avoid guessing paths. The garbled sentences weaken but do not contradict this.

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?

It has recognizable section labels (use case, exclusions, What it computes, Inputs, Outputs, Formula, fallback, docs) and front-loads the use case. But it is bloated and repetitive ('memorials and person-specific religious rights are not general rest' appears twice) and the three 'Example user requests' are unparseable fragments that add noise rather than value.

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?

With an output schema present, the description needn't explain return values, yet it still lists output fields, gives a complete JSON argument example, states the formula, and provides a REST fallback and docs link. For a 5-param, 3-required read-only calculator this is largely complete; only the broken negation keeps it from a 5.

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% and the description largely restates the same fields (start_date, end_date, include_* flags, work_schedule) already documented in the schema, including the work_schedule 'explicit Monday-Friday planning baseline' wording that duplicates the schema description. No extra syntax or constraint meaning is added, so 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 names a specific verb+resource ('auditable Croatia working-day count') and says plainly 'Counts authority-scope working and non-working dates in a range.' The country qualifier distinguishes it from the many sibling country count tools, though it never explicitly contrasts with count_hr_working_days' own family vs. 'add_*'/'check_*' variants.

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 opens with a clear when-to-use ('Use this when you need an auditable Croatia working-day count') and lists concrete exclusions (payroll, legal deadlines, future years, individual shifts). However, the key negative guidance is garbled and unparseable ('Do not use this when croatia 2026 article 1 general holidays over an explicitly selected Monday-Friday planning baseline'), so the primary when-not condition is effectively lost.

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