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

Annotations already declare readOnly/idempotent/non-destructive/openWorld, so the safety profile is covered. The description adds real behavioral value beyond that: it skips weekends and country/region holidays, reports exactly which days were skipped, and flags dates where independent sources disagree. It stops short of stating failure modes for bad country/region codes.

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?

A single front-loaded sentence that leads with the trigger condition and then layers use cases and behavior. Dense but every clause carries information; the enumeration of scenarios is slightly long for the payoff.

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 present, return values need not be explained, and the description still covers holiday handling, skipped-day reporting, and source-disagreement flags. It omits any routing guidance toward the sibling tools, which is the only meaningful gap.

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 all four parameters are already documented with format, sign convention, and magnitude limits. The description only reinforces 'N working days' and 'country or region', adding no syntax or edge-case detail 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?

States a specific verb+resource ('date N working days from another date') and immediately scopes it with holiday awareness, which separates it from siblings like check_business_day and list_public_holidays. An agent can identify the operation without opening the schema.

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?

Opening phrase 'Use this when the user needs...' plus concrete scenarios (delivery estimates, payment terms, notice periods, SLA/deadline questions) gives clear when-to-use context. It never names or excludes the sibling tools, so the agent must infer the boundary itself.

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