get_heart_rate

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. The description adds a genuine behavioral note that the samples series is 'large', warning of payload size, and implies the default is an aggregate-only response. It says nothing about missing-data behavior or permissions, so it adds moderate rather than rich context.

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 zero waste. The return contents are front-loaded and the expensive optional flag is flagged last, which is the right ordering.

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?

With no output schema, listing the returned metrics usefully stands in for a return-value spec. However, for a tool whose main input is a date, the absence of any date semantics leaves an agent guessing, so the definition is adequate but not complete.

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 parameter burden. It handles include_samples well (what it unlocks and its cost), but the date parameter is left entirely unexplained — no format, no timezone, and no statement that the default/null means today, which is a meaningful gap for the primary parameter.

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 specific verb and resource ('Get one day's heart rate') and enumerates the exact metrics returned (resting, min, max, 7-day resting average), which distinguishes it from siblings like get_heart_rate_zones and get_hrv by implication. It never names an alternative sibling explicitly, so differentiation is inferential rather than stated.

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 only guidance is parameter-level: use include_samples=true to get the intraday series. There is no statement about when to prefer this over get_heart_rate_zones or get_hrv, nor any prerequisite or data-availability caveat.

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