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

Annotations already declare readOnlyHint=true, openWorldHint=false, and destructiveHint=false, so the safety profile is fully covered. The description adds only that a category is returned alongside the numeric BMI, which is modest extra value for a pure calculation.

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?

A single front-loaded sentence with the action, resource, outputs, and unit system; nothing is wasted or buried.

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?

For a simple three-parameter calculator with no output schema, the description covers the inputs, the unit convention, and the returned values (BMI plus category). Only the absence of any routing against sibling health calculators keeps it from being fully complete.

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%, so weightLb, heightFt, and heightIn are already documented, giving a baseline of 3. The phrase 'in US units' is the only unit interpretation the description adds, and it merely reinforces what the schema already states.

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 (Calculate), resource (body mass index), and outputs (BMI and category) plus the unit system. The resource is distinct from nearby siblings like bmr_tdee and maintenance_calories, though the description never explicitly contrasts with them.

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?

The description says what the tool computes but gives no when-to-use guidance, prerequisites, or routing against the many sibling calculators (e.g. bmr_tdee, calorie). An agent must infer that BMI is the right choice here.

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