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

Annotations already cover read-only, idempotent, open-world, and non-destructive behavior, so the bar is lower. The description adds output-level context beyond annotations: it names the holiday when one exists and reports whether independent sources agree, which is useful behavioral information not implied by the hints.

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 sentences, front-loaded with the usage trigger and then the output behavior, with no wasted wording or redundancy.

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?

An output schema exists, so return values need not be explained, and annotations cover the safety profile. Parameters are fully documented. The only minor gap is that the description does not clarify its scope relative to the overlapping cross_check_holidays sibling, which reports source agreement too.

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 fully documents date, region, and country formats. The description adds no parameter-level detail (e.g., expected format or region/country interplay) beyond what the schema provides, so the baseline 3 is correct.

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+resource ('check whether a date is a business day') and scopes it to 'one specific date,' which separates it from list_public_holidays and add_business_days without needing to open either 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?

Gives explicit trigger conditions ('when the user asks whether one specific date is a working day, a public holiday, or whether businesses and banks are open'). It implies the single-date scope but does not name the alternative siblings (e.g., cross_check_holidays, list_public_holidays) for contrast, so no exclusions or named alternatives.

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