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

With no annotations, the description carries the full burden and does disclose meaningful behavior: weekends and national holidays are excluded, the range is inclusive, and each call costs 0.005 USD via x402. It omits return shape, country coverage semantics, date format expectations, and what happens on invalid input or out-of-range 'add' values, leaving significant gaps for a mutation-free but non-trivial computation 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?

Two tight sentences: the capability statement comes first, followed by the billing note. Nothing is repeated and no sentence is filler.

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?

Covers the two computation modes and the pricing model, which is the core of the tool. But with no annotations, no output schema, and ambiguous date input formats (the schema types allow string/number/boolean), the description leaves an agent guessing about accepted date formats, return value structure, and per-country holiday data coverage.

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 reported at 100%, so the baseline is 3; the schema itself carries the parameter definitions (including the 0-260 range for 'add'). The description adds only the inclusive-range semantics and the from/add relationship, which is modest value beyond the structured fields.

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: counting working days between two dates and/or computing date + N working days across EU/EEA/Nordic countries. This is clearly distinguishable from siblings like eu_holidays (holiday listing) and dk_bank_days (single-country variant), so an agent can select it without opening the schema.

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?

The 'and/or' phrasing implies the two operating modes (range count vs. add-N offset), which gives implied usage guidance. However, it never says when to prefer this over eu_holidays or dk_bank_days, nor any exclusion or prerequisite beyond the pricing note.

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