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

Annotations already cover safety and determinism (readOnly, idempotent, non-destructive, closed-world), so the bar is lower. The description does add two real behavioral facts beyond that — counting is inclusive of both endpoints, and the result surfaces which holidays were skipped — but says nothing about weekend definition, invalid-range handling, or what happens when from > to.

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?

One tight sentence with the core quantity front-loaded and no filler. It is a fragment missing an explicit verb ('Returns the number of...'), which slightly blunts clarity.

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?

Three required, fully documented parameters and no output schema, so the description carries the return-value burden — and it does say the output includes holidays skipped. It is still thin on edge-case behavior (weekend conventions, reversed ranges, unknown country codes) for what is otherwise a simple computation tool.

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%, with formats, ISO country code pattern, and examples already documented, so the baseline is 3. The description adds only the word 'inclusive' about the date range, which is genuinely useful but does not extend meaning on the country parameter or boundary behavior.

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 the specific quantity (working days between two dates) and the scope (per country, inclusive), which lets an agent distinguish it from add_business_days and is_business_day. It is a noun phrase rather than a verb-led statement, and it never names those siblings, so it stops short of a 5.

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 no explicit when-to-use guidance and no mention of the obvious alternatives (is_business_day for a single date, add_business_days for offsetting forward). The agent must infer from the name alone which of the three related tools fits its intent.

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