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

Annotations already declare readOnlyHint=true, idempotentHint=true, openWorldHint=false, and destructiveHint=false, so safety is covered. The description adds substantial behavioral context beyond annotations: deterministic calculation, the exact 2026-2027 authority-event scope, the working-day formula, and a REST fallback path. No behavior contradicts 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 guidance and structured into labeled sections, but it is longer than necessary and includes redundant material such as 'Inputs: date (date)' and an output-field list despite an existing output schema. The 'France France' typo and vague 'Example user requests: France: Bastille Day.' also detract from tight, polished conciseness.

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 simple one-date schema, the rich annotations, and the presence of an output schema, the description supplies everything an agent needs to select and invoke the tool correctly. It names the country scope, distinguishes national from regional/overseas calendars, states the computation rule, and provides a REST fallback and docs link.

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%, and the single date parameter is already documented in the schema as 'Gregorian date in France coverage.' The description repeats 'Inputs: date (date)' and provides a JSON example, but adds no semantic detail beyond what the schema already supplies. Baseline 3 is appropriate when the schema does the heavy lifting.

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: checking a date against the Saturday-Sunday baseline and exact 2026-2027 French authority events. It also scopes the tool to France national legal public holidays, which helps distinguish it from broader or regional calendar tools. However, it does not explicitly name sibling tools such as check_global_working_day or add_fr_working_days, and the 'France France' typo slightly weakens the exactness.

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 provides clear when-to-use guidance ('Use this when you need a deterministic France national legal public holidays result') and explicit when-not-to-use exclusions ('alsace-Moselle, overseas territories, employer, sector, school, bank, exchange and regional calendars'). It does not name specific alternative tools to switch to, which keeps it from a full 5.

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