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

Annotations already declare this is a safe, idempotent, non-destructive, closed-world read, so the safety profile is covered. The description adds the domain boundary against medical/pregnancy/children use, which is real value, but it never states the underlying assumption (e.g., linear loss at a fixed kcal-per-kg rate) or the return granularity (weeks vs days), which matters for a calculator whose output is only as good as its model.

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 first front-loads the trigger scenarios, the second handles exclusions. No filler, though the three quoted example phrasings are somewhat redundant with one another and could be trimmed to two.

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 three-parameter closed-form calculator with a fully documented schema, the description covers scope, inputs, and boundaries adequately. The only meaningful gap is the absence of any statement about the estimation model or the units of the result, which an agent might want to relay to a user.

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 units, ranges, and the default deficit (500, max 1,000) all documented in the schema itself. The description adds nothing about parameter semantics beyond echoing '500 calorie deficit' in an example, so the 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 conveys a specific function (estimating the duration required to lose a given amount of weight) and reinforces it with three concrete example phrasings. It does not explicitly name or differentiate itself from the sibling daily_calorie_target, but the timeline framing is distinct enough that an agent can distinguish 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?

It gives explicit trigger phrasing ('how long to lose 10 kg', '85 to 75 kg how many weeks') and an explicit exclusion list (medical plans, crash diets, children, pregnancy, medication questions). Both when-to-use and when-not-to-use are stated rather than left to inference.

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