Get HRV night

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

Annotations already declare readOnlyHint=true and openWorldHint=true, so safety is covered. The description adds genuine value beyond that by enumerating what the payload contains (last-night average, 5-minute high, weekly average, baseline band, status, plus per-reading data), which tells the agent what it will get back. It does not mention volume or whether readings can be numerous.

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?

Two short blocks, zero waste, with the core purpose front-loaded and the single parameter explained immediately after. Nothing redundant or padded.

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, and the description compensates by describing the returned summary fields and the per-reading series. For a one-parameter read tool this is nearly complete; only payload size/ordering behavior for the reading series is unstated.

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 0%, so the description must carry the burden, and it does: it gives the format (YYYY-MM-DD), the exact semantic ('the morning you woke up'), and the default (today). Only a residual ambiguity like timezone handling is left unaddressed.

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 concrete resource and scope: 'One night of heart-rate variability' with the summary metrics plus every sleep reading. The singular 'one night' implicitly distinguishes it from the plural garmin_get_hrv_summaries, but that sibling is never named, so the differentiation requires the agent to infer it from the name.

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 implies usage via 'one night' and the default-to-today behavior, but never states when to pick this over garmin_get_hrv_summaries or garmin_get_sleep, nor any prerequisites. Usage is inferable rather than explicit.

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