get_hrv_data

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

Annotations already declare readOnlyHint=true, destructiveHint=false, and openWorldHint=true, so the safety profile is known without the description. The description restates 'read-only' (redundant) and adds only the source system, Garmin Connect; it says nothing about failure behavior or data availability per date.

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?

Only two sentences, which is appropriately sized, but the date format is stated twice ('for cdate format YYYY-MM-DD' and 'Dates are YYYY-MM-DD'), wasting half the text on a duplicate. The useful content is front-loaded, which helps.

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?

For a single-parameter read tool with an output schema and full annotation coverage, the description supplies what is missing from the schema: the date format and the data source. Nothing an agent needs to make a correct call is absent.

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 0% — 'cdate' has no description, only a title — so the description carries the burden and does so by specifying the required YYYY-MM-DD format. That is the single most important semantic detail for this parameter, though it explains nothing about timezone or range limits.

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 ('Return') and resource ('HRV (Heart Rate Variability) data'), so the agent knows exactly what it fetches. It does not, however, distinguish itself from neighboring metric tools such as get_heart_rates, get_rhr_day, or get_daily_heart_rate_stats.

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 guidance on when to choose this tool over the many similar per-metric siblings, and no exclusion of alternatives. The only constraint given is the date format, which is parameter information rather than usage guidance.

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