get_heart_rate

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

No annotations are present, so the description must carry the behavioral burden. It does disclose the returned data (resting HR + intraday timeline) and the default-to-today behavior, but it omits details such as units, timezone handling, and response shape. This is adequate for a simple getter but not rich.

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 two compact sentences plus a minimal Args block. The main purpose is front-loaded and every clause adds necessary information.

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 one optional parameter, no annotations, and no output schema, the description covers selection and invocation well. It falls slightly short on specifying the intraday timeline's structure and units, but the tool is simple enough that the agent can still act 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 description coverage is 0%, yet the description fully documents the only parameter: format (YYYY-MM-DD) and default (today). This completely compensates for the schema gap.

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 begins with a specific verb and resource: 'Get a day's heart rate data' and adds the exact contents ('resting HR and an intraday HR timeline'). This makes it easy to distinguish from the sibling get_resting_heart_rate, which would only cover resting HR.

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 intended use—retrieving heart rate data for a day—is implied but never stated as a condition, and no alternatives are named. An agent must infer when to pick this over get_resting_heart_rate, get_daily_stats, or get_hrv.

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