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

Annotations already declare readOnly/idempotent/non-destructive/closed-world, so the safety profile is covered. The description adds genuine context beyond that: the cm-only input constraint with a conversion example, and the interpretive caveat that the output is a statistical range (±8.5 cm) rather than an individual prediction.

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 dense paragraph, front-loaded with the core definition before triggers, caveats and unit rules. Nearly every clause earns its place, though the formula and the three trigger phrases make it slightly long for a single-operation 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 carries the burden of describing the result and does so at a high level (an expected height with a ±8.5 cm range). The locale/clinical-disclaimer behaviour is documented in the schema, so the remaining gap is minor.

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 is 3, and the schema itself explains the sex param's ±13 cm role. The description goes further by fixing inputs to centimetres and showing a feet/inches conversion (5 ft 10 in = 177.8 cm), which resolves ambiguity the numeric schema alone leaves open.

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 computation (expected adult height) and the exact method (Tanner's mid-parental method), including the formula. An agent can distinguish it from siblings like growth_percentile or child_age without opening any schema.

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 explicit trigger phrasings ('how tall will my child be', 'mid-parental height', 'child height predictor') and equally explicit exclusions: it is a statistical range, not a forecast for one child, and says nothing about the child's current height. That cleanly routes the agent away from current-stature tools.

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