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

The annotations already establish readOnly, idempotent, non-destructive, and closed-world behavior. The description adds substantial behavioral context beyond those annotations: the exclusion of public-holiday defaults, the CLDR weekend-rule basis, the step-by-step formula, output fields, and a direct REST fallback. There is no contradiction with 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 description is front-loaded with usage and exclusions, then follows a scan-friendly structure with inputs, examples, outputs, formula, fallback, and docs. It is longer than necessary because the inputs and outputs sections largely duplicate the fully described schema and output schema, but the organization keeps it readable for a complex calculation tool.

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?

Given the tool complexity, full schema coverage, output schema, and annotations, the description is complete enough to select and invoke the tool correctly. It covers scope, exclusions, examples, inputs, computation behavior, outputs, and fallback documentation.

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 each parameter is already documented in the schema with type, examples, and constraints. The description repeats the inputs and gives a complete JSON example, but it adds little semantic meaning beyond what the schema already provides. The baseline score of 3 is appropriate.

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 states a specific verb and resource: adding or subtracting weekday-baseline working days for a CLDR territory. It directly distinguishes this from public-holiday, employer, bank, exchange, school, religious, and emergency-closure calendars, which is exactly the boundary needed among the sibling working-day tools.

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 explicit when-to-use guidance: a weekday-based date offset with public holidays excluded. It also gives explicit when-not-to-use guidance: when a public-holiday or other specialized closure calendar is required. Although it does not name the exact sibling tool, the condition maps unmistakably to the public-holiday sibling and is stronger than a generic context cue.

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