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

With no annotations, the description carries the full burden. It adds useful context by stating 'Pure/offline' and 'price 0.0 (free)', but does not disclose whether start and end dates are inclusive, how invalid date orders are handled, or the exact return format. These are significant behavioral gaps for a counting 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?

The description is extremely concise: a single front-loaded sentence stating the core function, followed by a brief note on offline/pricing. Every word earns its place with no redundancy or fluff.

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 simple three-parameter tool with no output schema, the description is largely complete: it states the function, exclusions, and special traits. However, it omits endpoint inclusivity and return value format, which are relevant for a counting tool. These omissions prevent a perfect score.

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 three parameters. The description adds minimal value by mentioning 'country holidays', which implies the country parameter influences the calculation, but it does not elaborate on parameter semantics beyond the schema.

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 explicitly states the tool counts business days between two ISO dates, excluding weekends and country holidays. This clearly distinguishes it from siblings like holiday_calendar_is_holiday (single date check) or holiday_calendar_next_business_day (finds next business day), using a specific verb and resource.

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 description implies the main use case (counting business days over a range) but provides no explicit when-to-use or when-not-to-use guidance. It does not mention alternatives like using holiday_calendar_is_holiday for single-date checks, leaving the agent to infer context from the tool name and siblings.

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