Get Garmin HRV

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

Annotations already cover the safety profile (readOnlyHint, openWorldHint=false), and the description adds real context beyond them: units in milliseconds (RMSSD), example HRV status values, that overnight readings are averaged per 30 minutes, and the wake-up-date keying convention. Missing is what happens when no data exists for the date, but overall this is well above the annotation baseline.

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 then lists the returned fields; every clause carries information. It is slightly list-heavy but has no filler or redundancy.

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 carries the burden of explaining returns and does so thoroughly: fields, units, status vocabulary, and aggregation granularity. Only the empty/no-data case and the exact response shape are left unspecified.

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 coverage is 100% and the date parameter already documents the wake-up-date meaning and today's-date default. The description reinforces the wake-up-date semantics ("like sleep") but adds no format, timezone, or range guidance beyond the schema, 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?

States a specific resource and scope: "One night's heart-rate variability from Garmin", then enumerates the payload (last-night average, 5-min high, 7-day average, baseline range, status, 30-min readings). The phrase "one night's" implicitly separates it from the sibling garmin_get_hrv_summaries, but that sibling is never named, so differentiation is inferred rather than explicit.

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 context is only implied: "Keyed by the wake-up date, like sleep" tells the agent how to select a day, and the singular "one night's" hints at the per-day use case. There is no explicit statement of when to choose this over garmin_get_hrv_summaries or garmin_get_day, and no mention of behavior for nights without a recording.

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