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

Annotations already declare readOnlyHint and non-destructive, and the description adds meaningful behavioral detail: pure computation, JSON return format, end-date exclusivity, weekend/holiday skipping, and inclusion of the holiday list. It also surfaces the monetary price, which is useful context beyond the schema.

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 tight and front-loaded, opening with the core behavior before adding output format and price. The price note is slightly non-essential for selection, but still relevant since this tool has a cost, so it earns its place.

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 two-parameter pure computation with no output schema, the description covers input format, date semantics, holiday rules, output content, side-effect profile, and cost. An agent has everything needed to decide whether to call it and what parameters to pass.

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?

While the schema describes start and end only as YYYY-MM-DD strings at 100% coverage, the description adds the range semantics: the tool counts business days between the two dates and excludes the end date. That extra interpretation is valuable for correct invocation, especially in edge cases around endpoint inclusivity.

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 clearly identifies a specific computation: business days between two dates, with explicit rules (exlusive of end, skipping weekends and US federal holidays) and a concrete result (the holiday list). This distinguishes it from any sibling tool by naming the exact operation and scope.

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 makes the use case obvious: whenever an agent needs US business days between two dates, including the holidays in the range. It does not explicitly discuss alternatives, but none of the sibling tools appear to offer a similar date calculation, so no exclusion is necessary.

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