Resting heart rate

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

Annotations already indicate readOnly, idempotent, and non-destructive. The description goes well beyond that by explaining the `coverage` block semantics: how to interpret `days_covered`, `span_days`, `window_satisfied`, and `more_available`. It warns about the pitfall of treating a limit-shaped window as the full data extent and instructs to quote `oldest_available` as the true start. This is rich behavioral detail that adds significant value beyond the annotations.

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 front-loaded with the core purpose, then introduces the coverage block. It uses a paragraph break to separate the primary function from the detailed coverage guidance. While the coverage section is lengthy, it is dense with necessary caveats and actionable instructions. The formatting with bold and emojis aids readability, and every sentence contributes to correct usage. It could be slightly trimmed but remains appropriately concise for the complexity.

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?

The description covers the essential output structure (per-day records and average), the coverage block, and edge cases around data availability. An output schema exists, so return-value details need not be spelled out. The only notable gap is the `fresh` parameter, which is left undefined. Given the tool's moderate complexity and the presence of annotations and output schema, the description is nearly complete but misses one parameter's semantics.

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?

The schema has 0% description coverage, so the description must compensate. It explains `owner` (filter by person) and `limit` (indirectly via 're-read with a larger `limit`'), but does not explain the `fresh` parameter at all. Since one of three parameters is completely unaddressed, and the other two are only partially described (limit's exact semantics of window size are implied rather than explicit), the description only partially compensates for the schema's lack of documentation.

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 clearly states the tool's function: 'Decrypt recent resting heart rate samples (bpm). Returns per-day records plus average over the window.' It names the specific metric (resting heart rate) and the output structure (per-day records and average), distinguishing it from sibling metric tools like get_hrv or get_wrist_temp. The verb 'decrypt' is specific and the resource is unambiguous.

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 provides clear usage context for the owner parameter ('Use `owner` prefix to filter by person') and gives detailed guidance on interpreting the coverage block, including when to re-read with a larger limit. However, it does not explicitly mention alternative tools or state when NOT to use this tool versus siblings like get_hrv or get_metric_trend. The name and title are self-explanatory, but explicit routing to alternatives is missing.

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