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

Annotations already declare readOnly, idempotent, openWorld and non-destructive, so the safety profile is covered. The description's behavioral additions — the 1000-business-day cap and 'start date is day 0' — are already stated in the schema, and the output schema covers the return values it mentions, so net new disclosure is modest.

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?

Front-loaded with the use case and examples before the constraints and exclusions, and every sentence carries information. The three separate example utterances are somewhat verbose for the point they establish.

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?

With a full output schema and annotated read-only semantics, plus limits, day-0 convention and usage exclusions in the description, an agent has everything needed to call this correctly.

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 baseline is 3, but the description adds routing guidance the schema lacks: pass the region 'when the user names one' and pass day count 'negative for earlier'. It lightly touches the remaining params without restating all schema detail.

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 precise verb+resource outcome: compute the date that falls a given number of business days from a start date. The scope ('after or before', country holidays, weekday/weekend logic) makes it unmistakable, and it is naturally distinct from count_business_days (offset vs count).

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 with three concrete user phrasings, plus negative guidance ('Do not use it for legal deadlines that follow their own court or contract rules, or for calendar-day offsets'). An agent knows exactly when this tool applies and when it does not.

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