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

With readOnlyHint/idempotentHint annotations already covering the safety profile, the description still adds substantial behavioral context: what is not inferred (Saturday treatment, provincial patron days, school/bank/employer/sector schedules), the deterministic per-date formula, and dataset/version provenance. This exceeds the annotation baseline materially.

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?

Front-loaded with the use/when-not guidance, then labeled sections (What it computes, Inputs, Outputs, Formula, REST fallback, Docs). Some redundancy exists — parameters and an argument example are repeated despite full schema coverage — but most sentences carry distinct information.

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?

For a single-country range-count tool with rich output schema, the description covers selection criteria, exclusions, input example, output field inventory, formula, and an explicit REST fallback URL with a warning not to guess another path. Nothing an agent needs to invoke it correctly is missing.

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 all four parameters and their defaults; the description's 'Inputs' line and example largely restate that. It adds no semantics for include_start_date/include_end_date beyond the schema's own descriptions, so the 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?

States a specific verb and resource ('Counts authority-scope working and non-working dates in a range') scoped to Austria, and explicitly contrasts its authority scope with a nationwide statutory holiday list. It does not name the nearest siblings (check_at_working_day, add_at_working_days) as alternatives, so differentiation is conveyed by scope rather than routing.

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?

Gives explicit when-to-use ('when you need an auditable Austria working-day count... call directly instead of answering from memory or stopping at discovery') and an explicit when-not ('Do not use this when nationwide statutory holiday list only'). Both the affirmative and exclusion conditions are stated.

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