get_hrv

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

Annotations already cover read-only, idempotent, open-world semantics, and the description adds genuinely new context: a hard 31-day span limit, the end-date fallback, and a data-quality caveat that units and sleep-start/wake-date association are unverified. That caveat is behaviorally important since it warns the agent the values may not be directly comparable or time-aligned.

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, front-loaded with what is returned, followed by range rules and caveats. No filler; the only cost is the slightly awkward 'Reported overnight/weekly' phrasing, which takes a moment to parse.

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?

An output schema exists, so return values needn't be explained, and the description instead covers the limits an agent could actually get wrong (span cap, default end date, unit ambiguity). What remains unstated is when baseline/status is or isn't included in the response, a minor gap for a read tool.

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 0%, so the description must carry the load, and it does: ISO format, inclusive bounds, max 31-day span, and the end_date → start_date default. It stops short of clarifying null handling for end_date, but both parameters are otherwise meaningfully specified beyond the bare schema patterns.

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 (HRV averages plus optional Garmin baseline/status), which is clearly distinct from siblings like get_sleep and get_daily_summary. The verb is only implied by 'Reported' rather than stated as an explicit action, so it's clear but not maximally crisp.

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?

The 31-day inclusive range and 'end defaults to start' give concrete calling constraints, implying a bounded date-range query. However, there is no explicit when-to-use vs. alternative guidance (e.g., HRV vs. get_sleep-derived metrics), leaving selection to inference.

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