Get daily stress (date range)

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

Annotations already declare readOnlyHint, idempotentHint, and non-destructive, so safety is covered; the description adds real value by disclosing the return shape (one entry per day, calendarDate plus values map), the units of each duration field in seconds, the 0–100 scale, the HRV derivation, and the 28-day cap. Only error behavior and empty/no-data handling are left unstated.

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 sentence that front-loads the resource and result shape before the constraint. It is long but every clause carries information; only the 28-day limit is redundant with the schema.

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 takes on the burden of explaining the return value and does so concretely (field names, units, ranges). What remains missing – pagination behavior beyond the 28-day cap, empty-day handling, and any auth/permission notes given openWorldHint=true – is minor but not trivial.

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 startDate and endDate are already documented as inclusive, YYYY-MM-DD, user-local, and bounded by 28 days. The description restates the 28-day maximum, which is duplicative rather than additive, 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 names a specific verb and resource ('Get daily stress statistics for a date range') and immediately describes the shape of the result, so an agent knows what comes back. The resource (stress) is lexically distinct from nearby siblings like garmin_get_hrv or garmin_get_body_battery, but the description never explicitly contrasts them, so it sits just below 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?

There is no explicit guidance on when to call this versus alternatives in a crowded sibling set (hrv, hrv_summaries, daily_summary, body_battery all overlap in wellness territory). The 28-day limit is stated, but as a constraint, not a usage rule.

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