Get heart rate

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

Annotations already declare a safe, idempotent read, but the description adds genuinely new behavior: a 30-day range cap per call, raw resolution truncating at 2000 samples, latest:true overriding all other arguments, and the meaning of a truncated:true response. These are operational constraints not present in the annotations or schema.

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?

Front-loaded with the core purpose before the usage routing and edge cases. It is a single dense paragraph with heavy parenthetical enumeration of sources and stats; every clause carries information, though it could be broken into sentences for easier scanning.

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, the description carries the return-value burden and does so: it names the returned fields (avg/min/max bpm, dominant source, overall and per-source stats) and the truncated flag. Combined with defaults, limits, and the sibling routing, an agent has everything needed to call it correctly.

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 100%, so the baseline is 3, but the description adds real meaning beyond the schema: it clarifies that latest:true causes other arguments to be ignored, that raw returns individual samples capped at 2000, and that buckets are aligned to local time. The interaction between latest and the other params is not derivable from the schema alone.

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+resource (get the heart-rate time series) and immediately qualifies the shape of the result: bucketed aggregation with avg/min/max bpm, dominant source, and per-source stats. It also explicitly distinguishes itself from list_sleep_periods for overnight/HRV use cases, so an agent can differentiate it from siblings without opening schemas.

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?

Gives concrete when-to-use cases (at particular times, during a workout, across a day) and an explicit when-not with a named alternative (overnight averages, lowest HR, HRV → prefer list_sleep_periods). It also states defaults (last 24h at hourly) and the 30-day per-call range limit, leaving little to inference.

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