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

Annotations cover the safety profile (readOnly=true, idempotent=true, destructive=false), and the description adds genuinely new behavioral detail: the start date is not counted, negative values count backward, 0 returns the start date or the next business day, and the range is capped at 1,000 days. It also discloses the return content ('the resulting date and every holiday it skipped'), which matters since there is no output 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?

Three sentences, each carrying distinct information: scope/use cases, counting convention with edge-case example, and output/limits. Nothing is repeated from the name or title, and the core behavior is front-loaded.

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 date-arithmetic tool with no output schema, the description supplies everything an agent needs: counting semantics, direction, limits, holiday handling, and the return shape. No meaningful gaps remain.

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 coverage is 100%, so the baseline is 3, but the description adds real semantic value: it clarifies the off-by-one convention with a worked example ('1 business day after a Friday is the next Monday, or Tuesday when that Monday is a holiday') and restates the ±1,000 bound. The negative-direction and zero-case behavior is meaningfully reinforced beyond the schema text.

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 and resource ('Move a number of U.S. business days forward or backward from a date') and pins down the scope with 'skipping weekends and observed federal holidays'. This clearly separates it from count_business_days and check_business_day, which measure rather than shift a date.

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?

Names concrete use cases ('due dates, delivery windows and notice periods'), which tells the agent when this tool is appropriate. It stops short of explicit when-not guidance or naming a sibling alternative, so it is clear context rather than full routing.

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