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

Annotations already declare readOnlyHint, idempotentHint, openWorldHint=false and destructiveHint=false, so the safety profile is covered. The description goes beyond them by disclosing the computation formula, the output field set, an exact REST fallback endpoint, and a documentation link — useful operational context for a calculation tool.

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-loads the usage condition, then moves through inputs, example payload, outputs, formula and fallback in labeled chunks, which makes it skimmable. The single-line formula and the REST/docs block are marginally redundant given the schema and output schema, but nothing is padded to the point of noise.

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 scoped date-count calculator with a full output schema present, everything an agent needs is covered: when to call it, what it computes, the exact argument shape, the returned fields, and a deterministic HTTP fallback if the tool call fails. No material gap remains.

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 coverage is 100% and each parameter already carries a description and default, so the baseline is 3. The description adds a complete, copy-ready JSON argument example using all four fields, which clarifies how include_start_date/include_end_date interact with the required date range beyond what the schema spells out.

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' — and names Italy both in the title and via the tool name. It does not, however, explicitly differentiate itself from the many adjacent siblings (count_de_working_days, check_it_working_day, add_it_working_days), leaving the agent to infer the count/check/add distinction from naming alone.

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 clear positive guidance ('Use this when you need an auditable Italy working-day count... instead of answering the formula from memory') and an explicit when-not clause about non-inferred regional, municipal, school, bank and employer-specific schedules. The negative clause is awkwardly worded and never names a concrete alternative tool, so routing among siblings still requires inference.

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