get_hrv

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

Annotations already declare readOnlyHint=true and openWorldHint=true, so the safety profile is covered and the description only needs to add operational context. It does add useful behavior — the default response is a summary plus a status, and setting include_samples expands it to per-reading data — but it omits the important case of what 'date=null' defaults to (presumably last night) and any hint about data availability.

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 sentences with the primary purpose front-loaded and the optional-parameter instruction immediately after. Nothing is redundant and no sentence could be cut without losing signal.

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, so the description must frame the return value, which it does ('summary and status' vs individual overnight readings). Given a two-parameter read-only tool, this is sufficient to invoke it correctly; the only mild gap, the date default, is small against the tool's simplicity.

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 carries the full burden of explaining both parameters. It explains include_samples well (toggles individual overnight readings) but says nothing about the date parameter's expected format or default behavior when null, leaving one of two parameters undocumented in both schema and description.

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 names a specific resource and scope: 'one night's heart rate variability (HRV) summary and status', which tells an agent this returns a single-night aggregate rather than raw streams. It does not name or distinguish itself from the sibling get_hrv_range, which covers multi-day queries, so the agent must infer the split from the names alone.

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 guidance is implied rather than stated: 'one night's' signals a single-date query, and the description explicitly directs the agent to set include_samples=true when it wants individual overnight readings. It never says when to prefer this over get_hrv_range, nor what happens if the optional date is omitted, so the agent cannot be fully confident about selection.

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