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

Annotations already establish readOnly, idempotent, and non-open-world behavior. The description adds genuine value beyond them by disclosing that three formulas (Mosteller, Du Bois, Haycock) are returned and that both unit systems are supported, which an agent cannot derive from the annotations or schema alone.

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?

Three short sentences with the worked example front-loaded, which is efficient. However, the leading example is a weak substitute for a purpose statement, and the trailing web-page URL is promotional padding that does not help an agent invoke the tool.

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, the description partially compensates by showing a sample result (1.82 m²) and naming the three returned formula values, so an agent can anticipate the return shape. The remaining gap is the absence of any explicit statement of which inputs map to which units.

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 the schema already documents all five parameters and their bounds. The description only echoes units (metric/imperial) and implies height/weight, adding no syntax, ranges, or semantics beyond the schema. 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 never states the verb directly; it relies on an example ('A person 170 cm tall weighing 70 kg has a body surface area of 1.82 m²') plus formula names to imply that it computes BSA. The resource is clear from the name/title, but there is no explicit statement of what the tool does and no differentiation from siblings like bmi_calculator, body_fat_calculator, or lean_body_mass_calculator.

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 guidance on when to use this tool versus related body-metric calculators, nor on which formula to prefer or when to pick metric vs imperial. The reader must infer all usage context.

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