Heart rate variability

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

Beyond the annotations, the description discloses that data comes from a local cache, that 5-minute readings may be fetched from Garmin when older than the synced detail window, the default and maximum ranges, and the compatible-watch requirement. This is rich behavioral context for a read-only tool.

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 front-loaded with the core purpose and return values, then proceeds to parameter effects and constraints. Every sentence adds useful information without 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?

There is no output schema, but the description thoroughly explains the returned HRV metrics and the optional 5-minute readings. For a read-only cache-backed tool with clear annotations, nothing essential is missing.

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 already 100%, so the baseline is 3. The description adds useful meaning beyond the schema by explaining the readings_date effect, the 28-night default, and the 366-night cap, though it does not discuss response_format.

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 states a specific verb and resource: get nightly HRV from the local cache. It enumerates exactly what is returned (last-night average, highest 5-minute value, 7-day average, baseline range, and Garmin status), making it distinguishable from broader health/recovery siblings.

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 clear: default date range, maximum per call, how readings_date changes behavior, and the hardware prerequisite. It does not explicitly name alternative siblings such as recovery trends, but the conditions for correct use are well explained.

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