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

Annotations already declare readOnly, idempotent, non-destructive, closed-world. The description goes further by disclosing the exact formula (one day at a time, decrement only on is_working_day=true), coverage limits, and a direct REST fallback endpoint, which is genuinely useful operational context beyond 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?

Front-loaded with the key when-to-use guidance, but padded with redundant sections ('Example user requests', 'Inputs', 'Complete JSON argument examples') that duplicate what the schema already supplies. The 'Example user requests' line is awkward filler that does not earn its place.

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, the description needn't detail returns, yet it lists output fields (harmless redundancy). It fully covers the tool's scope, formula, and coverage caveats, giving the agent enough to invoke correctly; only minor bloat keeps it from a 5.

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 itself documents both parameters (including 'start date excluded for non-zero offsets'). The description merely restates the input names and one JSON example, adding no meaning beyond the structured fields, so the baseline 3 applies.

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 (Argentina working-day offset) and explicitly scopes it as the 'nationwide default' authority-scope calendar. An agent can distinguish it from add_br_working_days or add_at_working_days purely by the country/scope qualifier.

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?

Explicitly directs the agent to call the tool and return its result instead of computing from memory, and adds a clear when-not clause (provincial/municipal/employer/bank/sector schedules and regional one-off holidays are out of scope). Both the affirmative and negative conditions are present.

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