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

Annotations already declare readOnlyHint=true, idempotentHint=true, and openWorldHint=false, so the safety profile is covered. The description goes beyond that by disclosing what the computation actually produces — three formula variants side by side plus calorie needs at five activity levels — which tells the agent the return shape despite there being no output schema. It stops short of noting the optional bodyFat dependency behavior or the metric/imperial parameter duplication.

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?

Two sentences, the substance front-loaded and the URL relegated to the end. Every sentence carries information, though the trailing promotional web-page link is marginal for an agent's decision-making.

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 no output schema and a stateless, read-only calculator, the description does the heavy lifting by enumerating the returned values and formulas. Combined with the fully documented schema, an agent has enough to invoke it correctly; only the unit-input interplay is left implicit.

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% with 9 documented parameters, so the baseline is 3. The description adds a little meaning (bodyFat feeds Katch–McArdle, and calorie output is generated at five activity levels rather than via a parameter), but it does not explain the metric/imperial switch or why both cm and ft/inch and kg and lb coexist.

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 names a specific resource (basal metabolic rate), the three named formulas (Mifflin–St Jeor, revised Harris–Benedict, Katch–McArdle), and the additional output (daily calorie needs at five activity levels). That is far more specific than a bare name restatement. It does not, however, distinguish itself from close siblings such as tdee_calculator, calorie_deficit_calculator, or macro_calculator, which an agent could easily confuse it with.

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?

There is no when-to-use statement, no prerequisites, and no named alternative. With many overlapping fitness/energy siblings (tdee_calculator, calorie_deficit_calculator, calories_burned_calculator, macro_calculator), an agent gets no routing help about when BMR is the right tool versus those.

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