Resting heart rate per day over a date range, as { calendarDate, value } rows. Reshapes allMetrics.metricsMap into [{calendarDate, value}], dropping null values.
| Name | Required | Description | Default |
|---|---|---|---|
| end | Yes | Calendar date, YYYY-MM-DD (UTC) | |
| start | Yes | Calendar date, YYYY-MM-DD (UTC) |
Changes observed during successful MCP inspections.
Does the description disclose side effects, auth requirements, rate limits, or destructive behavior?
Annotations already declare readOnlyHint=true and openWorldHint=true, so safety is covered. The description adds genuinely useful behavioral context beyond them: it discloses that null values are dropped, which tells the agent that no-data days are absent from the array rather than present as nulls.
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, zero waste, with the primary purpose front-loaded and the return shape following. Size is well matched to a simple two-parameter read tool.
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 correctly compensates by specifying the row shape `{ calendarDate, value }` and the null-dropping behavior. Only minor gaps remain (e.g., no note on extremely long ranges or empty results), which are low-stakes for this tool.
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 100% and both parameters are documented with format and UTC semantics, so the baseline is 3. The description adds nothing about start/end beyond what the schema already provides.
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+granularity: 'Resting heart rate per day over a date range'. The range-versus-single-day phrasing implicitly differentiates it from the sibling get_rhr_day, but it never names that sibling, so the routing is left to inference.
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?
No when-to-use, when-not-to-use, or alternative is stated. The most likely confusion, this tool vs. get_rhr_day (single day vs. range), is left unresolved for the agent.
Agents often have multiple tools that could apply. Explicit usage guidance like "use X instead of Y when Z" prevents misuse.
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