get_hrv

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

No annotations are provided, so the description bears full responsibility for behavioral disclosure. It mentions the data source (Garmin) and the outputs (status, baseline range), but does not disclose critical behavioral traits such as read-only nature, authentication requirements, data freshness, or what happens when no data exists for a given day. The description is insufficient for safe autonomous use.

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 concise at two sentences plus an Args line. It front-loads the core purpose and parameter guidance without extraneous information. Every part serves a clear function, though it could be slightly more structured for readability.

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?

Given the existence of an output schema, the description need not detail return values. However, it creates confusion by stating 'for one night' while the parameter is named 'day'. It does not explain what 'Garmin's status' or 'personal baseline range' entail. With siblings like get_sleep and get_stress, the description could better tie the tool to overall health analysis. It is adequate but has notable gaps.

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 supplement. The 'Args' section provides examples for the 'day' parameter ('today', 'yesterday', '2026-08-18'), adding format and possible values beyond the schema's bare type and default. However, it does not explain edge cases like future dates or missing data, so compensation is partial.

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 clearly states the tool returns 'Heart rate variability (HRV) for one night, with Garmin's status and the personal baseline range.' This specifies the verb (get), resource (HRV), and scope (single night, with status and baseline). It distinguishes from siblings like get_heart_rate and get_stress by focusing on a specific recovery metric with contextual data.

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 description provides no explicit guidance on when to use get_hrv versus alternative tools such as get_stress or get_body_battery. It explains that HRV is a recovery and stress indicator, which implies usage context, but does not state when to prefer this tool over others or when not to use it.

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