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

Annotations already establish readOnly, idempotent, non-destructive, and closed-world, so the safety profile is covered. The description adds genuinely new behavioral context: the deterministic formula (weekend baseline plus published full/half-day holidays), the 2026-2027 dataset scope, half-day handling at 13:00, and a pinned REST fallback. It does not state out-of-range date behavior, which would have made this a 5.

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?

Well front-loaded: purpose and exclusions come first, then computation, examples, inputs, outputs, formula, and fallback. It is longer than necessary because the full output-field list duplicates the existing output schema and the REST/docs lines add bulk, but every section is labeled and scannable rather than rambling.

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 single-parameter deterministic check tool with annotations and an output schema, the description supplies everything needed: use/no-use conditions, coverage window, formula, example request, and a fallback endpoint. Return values are already covered by the output schema, so the extra enumeration is harmless redundancy rather than a 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% for the single `date` parameter, so the schema already carries the semantics and 3 is the baseline. The description's 'Inputs: date (date)' plus the JSON example largely restate what the schema and its example already show, adding only the coverage-window emphasis.

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 ('checks a date against Türkiye's statutory public holidays and explicit 13:00 half-day events') and pins the coverage window to 2026-2027. It also explicitly scopes out adjacent calendars (company, school, bank, exchange, collective-agreement, local), so an agent can distinguish it from the broader working-day family without opening a 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?

It gives an explicit when-to-use ('when you need Türkiye national statutory public-holiday status'), a when-not ('company, school, bank, exchange, collective-agreement or local closure calendar'), and an operational instruction to call the tool directly rather than answering from memory. It does not, however, name sibling alternatives such as add_turkey_working_days or count_turkey_working_days for range/counting needs, so the routing is slightly incomplete.

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