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

Annotations already establish that the tool is read-only, idempotent, and closed-world. The description adds meaningful behavior beyond that: pricing and payment rail, data provenance from Nager.Date and date-holidays, verified African calendars with observed days and declared Islamic holidays, and the returned date/name fields. It does not mention rate limits or error behavior, so it stops short of full transparency.

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 purpose is front-loaded in the first sentence, and the remaining sentences add coverage, data-source, use-case, and pricing context. It is somewhat list-heavy and repeats coverage information across geographic enumerations, but the structure remains readable and no sentence is entirely irrelevant.

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 simple two-parameter read-only tool with full schema coverage and annotations, the description supplies the main missing context: payment cost, geographic scope, verified calendar distinctions, and returned fields. It would be stronger if it explicitly noted the year-range limitations or routed agents to related business-day tools, but it is broadly complete.

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%, and the schema already documents the year ranges, ISO country codes, default country, and verified-country list. The description only broadly restates country and year coverage, adding no parameter-level syntax or constraints beyond the schema. It even says 'any country and year,' which is looser than the schema's explicit ranges, but the schema carries the precise semantics.

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 a specific resource and scope: public holidays for a country and year, returning dates and English names. It is easy to distinguish from validation or business-day tools by subject matter, but it does not explicitly contrast itself with siblings such as za_is_business_day or za_count_business_days.

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?

The description gives implied use cases such as scheduling, payroll, and deadlines. However, it does not state when to use this tool instead of related siblings, nor does it mention exclusions or conditions for choosing holiday listings over business-day calculations.

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