Fetch daily resting heart rate values for a Garmin Connect date range, returning calendarDate and value pairs while dropping null entries.
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?
The readOnlyHint annotation already establishes this as a safe read. The description does add one behavioral detail beyond the annotations — that null values are dropped — and hints at the output shape. However, it omits pagination, ordering, and completeness behavior for the date range, so the added context is thin.
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 single clause is compact and wastes no words, but it leads with internal implementation jargon (allMetrics.metricsMap) that a caller will not recognize. Brevity here shades into under-specification rather than disciplined conciseness.
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 burden of explaining what the tool returns, yet it never names resting heart rate and instead describes an undocumented internal field. For a simple date-range tool it omits the domain context and the sibling differentiation an agent needs, leaving it materially incomplete.
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%, so start and end are already documented as YYYY-MM-DD UTC dates. The description adds nothing about parameter semantics, which is the expected baseline when the schema carries full coverage.
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 describes an internal data transformation ('reshapes allMetrics.metricsMap into [{calendarDate, value}]') rather than the tool's domain purpose. It never states that this returns resting heart rate data, and 'reshapes' is an implementation verb, not a user-facing one. It also fails to distinguish this from the near-identical sibling get_rhr_day.
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?
There is no when-to-use guidance, no prerequisites, and no mention of the closely related get_rhr_day alternative. An agent has no basis for choosing between get_rhr_daily and get_rhr_day since the description offers neither scope nor differentiation.
Agents often have multiple tools that could apply. Explicit usage guidance like "use X instead of Y when Z" prevents misuse.