garmin_body_metrics

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

Beyond the readOnlyHint/openWorldHint annotations, the description adds a genuinely useful cost signal: 'Makes about 3 Garmin requests per day', letting an agent estimate load for large 'days' values. It also clarifies a structural quirk — most fields are per-day while fitness age is a single current value, and weigh-ins are only present 'any' day one exists. It does not discuss auth requirements or failure behavior, so not a 5.

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 tight sentences; the payload of returned fields is front-loaded and the cost note is placed at the end where it is easy to scan. The long field enumeration is dense but each item earns its place by telling the agent what data is available; only the trailing 'plus current fitness age' is slightly ragged in structure.

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 an output schema present and annotations covering safety and open-world scope, the description only needs to convey content and cost — both are covered. The remaining gap is that it never says how the per-day records are aggregated or ordered, though the output schema likely resolves that.

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?

The single 'days' parameter already has a full schema description ('Number of past days, including today') at 100% coverage, so the baseline is 3. The description's 'per day' wording reinforces the day-granularity interpretation but adds no format, range, or default detail beyond the schema.

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 enumerates the exact data returned (body battery, steps vs. goal, distance, calories, floors, stress, HR range, intensity minutes, respiration, SpO2, weigh-in, fitness age), which makes the resource unambiguous and implicitly separates it from siblings like garmin_sleep, garmin_readiness and garmin_hr_zones. It lacks an explicit verb (e.g. 'returns'/'fetches') and never names a sibling for direct contrast, so it falls short of a 5.

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?

Usage is only implied by the field list — an agent can infer 'use when you need daily wellness summaries', but there is no explicit when-to-use statement, no condition selecting it over garmin_sleep or garmin_readiness, and no exclusion guidance. The 'per day' framing with the default of 3 days gives a hint about granularity but not about tool selection.

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