Weight and body composition

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

Annotations already declare readOnlyHint, idempotentHint and destructiveHint=false, so the safety profile is covered. The description adds genuinely useful context that the composition metrics are conditional ('where a scale records them'), meaning fields may be absent. It does not cover behavior for days with no weigh-in or the response shape.

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?

One front-loaded sentence with no filler; the key qualifier about which metrics are returned is placed immediately. It is arguably a touch terse for a tool whose output fields are variable, but nothing is wasted.

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 only two date parameters, full schema coverage, no output schema and annotations covering safety, the description is nearly sufficient. It still leaves open whether missing-scale days yield empty entries or omitted fields, which matters for parsing the variable composition data.

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%: both start_date and end_date are documented including inclusive semantics and the default-to-today behavior. The description's 'over a range' adds nothing the schema doesn't already say, 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?

Names the specific resource (weigh-ins) and enumerates the returned metrics (body fat, muscle mass, BMI), which clearly separates it from siblings like get_body_battery or get_steps. The verb is only implied by 'over a range' rather than stated as 'retrieve/list', and no sibling is named.

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 statement of when to use this versus other body-metric tools, no prerequisites (e.g. a connected scale), and no exclusions. The date-range scoping is the only implied usage signal.

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