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

Annotations already establish read-only, idempotent, non-destructive behavior, and the description adds useful behavioral context: default calendar selection, unknown calendar ids are errors, and calendar-specific exception handling. It does not cover every edge case, but it adds meaningful transparency beyond the annotations.

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 first sentence front-loads the result, but the paragraph repeats schema information such as the day range and the us-fed-banking calendar exception. The ambiguous 'days=1 always leaves the start date' phrasing also costs clarity rather than earning space.

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 an output schema and full parameter descriptions already present, the description supplies the key day-count convention, default calendar, and calendar exception behavior. It is nearly complete for calling the tool, though the day=1 wording could be clearer.

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. The description adds real semantic value by explaining that the start date is day 0 and by describing the calendar default, though it also repeats some schema details and the 'days=1 always leaves the start date' phrasing is ambiguous.

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 states the operation: it returns the date that is N business days after a start date, with day-count semantics tied to Excel WORKDAY. It does not explicitly distinguish itself from siblings such as count_business_days or roll_date, so it is clear but lacks sibling differentiation.

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?

It gives parameter-level guidance such as omitting calendar for the default us-federal-opm, but it never says when to use this tool instead of count_business_days, roll_date, or other date utilities. The agent must infer tool selection from the name and description alone.

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