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

Beyond the read-only annotations, it discloses billing behavior: $0.01 per call, first 25 free, failed calls free, and repeats are not free. It also states that the tool only reads or computes and changes nothing, which aligns with and enriches the annotation profile.

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 core purpose and outputs are front-loaded, followed by limitations, usage context, an example, and pricing. It is generally efficient, though the pricing and no-mutation sentences overlap slightly and one sentence reads more like product positioning.

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?

There is no output schema, so the description carries the burden of explaining return values; it does so by naming BMI, WHO adult category, and the normal weight range. It also states the adult-only and screening-not-diagnosis constraints, making the definition complete for correct use.

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%, so the baseline would be 3 even with no additional detail. The description adds a concrete example (weight=70, height=175) and restates metric/imperial unit conventions, which lightly clarifies invocation but largely duplicates the schema.

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 clearly states that it computes body mass index from weight and height and returns the WHO adult category plus the normal weight range for that height. It is specific enough to distinguish from generic calculators, though it does not explicitly compare itself to siblings such as units_convert.

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 clear usage context (health, fitness and nutrition apps) and an important limitation (for adults; screening, not diagnosis). It does not name alternatives or say when another sibling tool would be preferable, but the intended use case is clear.

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