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

Annotations already declare read-only, idempotent, non-destructive behavior. The description goes further by disclosing the calendar scope limitation (federal/authority-level only, not state/municipal/sector/employer), the output fields, dataset version, and a REST fallback, giving the agent rich behavioral context. No contradiction with 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 organized into labeled sections, but it is lengthy and includes redundant content such as the full output field list (when an output schema exists) and a trivial formula, which dilute 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 tool's complexity, the presence of an output schema, rich annotations, and many siblings, the description covers purpose, usage, scope limitations, inputs, outputs, and fallback methods. An agent has everything needed to invoke and interpret the tool.

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 each parameter with descriptions and examples. The description repeats the parameter list and provides a complete JSON example, but adds no semantic detail (e.g., date inclusivity rules) beyond what the schema provides, 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?

The description states a specific verb ('Counts') and resource ('authority-scope working and non-working dates in a range') for Brazil. It implicitly distinguishes from check_br_working_day (single date) and add_br_working_days by emphasizing range counting, but it does not name any sibling explicitly.

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 a clear when-to-use ('when you need an auditable Brazil working-day count') and when-not ('Do not use this when this is not a universal Brazilian private-employer calendar...'). However, it does not name alternative tools such as check_br_working_day or add_br_working_days for different needs, so it falls short of the top score.

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