fitness_body_composition

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

Beyond the annotations (readOnly, idempotent, non-destructive), the description reveals it reads from Garmin and Apple Health, shows per-date values plus trend (difference between first and last), and expects monthly usage. No contradictions with annotations.

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?

The description is concise, with a clear purpose paragraph and structured Args/Returns section. While slightly informal and in Spanish, it is efficient and front-loaded.

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?

Given the tool's complexity (two data sources, trend calculation) and absence of an output schema, the description fully explains what data is returned (series by date, trends for weight/fat/muscle) and error handling. It covers all necessary context for an AI to use it correctly.

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?

With schema description coverage at 0%, the description compensates well by explaining start (YYYY-MM-DD), end (optional, defaults to start+6 days, but suggests wide range), and response_format. This adds clear meaning beyond the schema's bare descriptions.

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 clearly explains the tool tracks evolution of weight, fat %, and muscle mass over a period, combining data from Garmin and Apple Health. It specifies monthly tracking vs daily weighing, distinguishing it from siblings like garmin_add_body_composition.

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?

Description states it is designed for monthly tracking—not daily weighing—and recommends a wide date range (e.g., 3 months) for trend analysis. However, it does not explicitly name alternative tools or state when not to use it.

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