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

Annotations already cover safety (readOnly, idempotent, non-destructive, non-open-world). The description adds genuine scope disclosure: what is NOT computed (individual shifts, replacement weekly rest, employer/local/sector schedules, payroll, legal deadlines, future years), plus a REST fallback path and docs link. This is real behavioral context 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?

The description is bloated with template fragments and broken sentences (e.g. 'Add or subtract Croatia working days around Good Friday is not a general statutory holiday,' 'Do not use this when croatia 2026 article 1 general holidays over an explicitly selected Monday-Friday planning baseline'). Example requests, output field lists, formula, REST path, and docs are all crammed in without clear front-loading; several sentences do not earn their place.

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?

The scope boundaries and coverage limitations are meaningfully covered, and an output schema exists so return values need not be explained (the long output-field dump is redundant). However, the malformed exclusion clause and cluttered structure leave the when-not guidance incomplete for an agent deciding between this tool and the count/check siblings.

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 all three parameters are already documented in the schema; the baseline is 3. The description restates the inputs and adds the constraint that mon_fri_planning is required and not an individual statutory roster, but contributes little beyond what the schema already supplies.

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 and resource: 'Adds or subtracts Croatia authority-scope working days in exact coverage,' and the opening line frames it as a deterministic Croatia working-day offset. This clearly distinguishes it from sibling check_hr_working_day and count_hr_working_days, though that distinction is left implicit rather than named.

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?

There is a usable when-to-use instruction ('Call this tool directly and return its calculation instead of answering from memory') and an attempt at a when-not clause, but the exclusion sentence ('Do not use this when croatia 2026 article 1 general holidays over an explicitly selected Monday-Friday planning baseline') is grammatically broken and its condition is not parseable. Guidance exists but is partly garbled.

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