Get daily hydration (date range)

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

Annotations already declare readOnly/idempotent/non-destructive, so the bar is lower, and the description still adds real context: the 31-day maximum and the fact that sweatLossInML is estimated from activities rather than logged. It does not describe ordering or pagination behavior, but for a bounded date-range read that is minor.

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?

Three sentences, front-loaded with the core purpose, and the field enumeration earns its space because there is no output schema. The field list is dense but not padded.

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 return-value burden and does so by naming each field and clarifying the two non-obvious ones (consumed value, estimated sweat loss). The range cap and data-availability caveat round it out; only timezone/ordering details are left implicit.

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 fully documented there, including inclusive bounds and local-calendar formatting. The description only restates the 31-day cap, adding nothing about startDate/endDate semantics beyond the schema, so baseline 3 applies.

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 and resource ("Get logged water intake per day") and enumerates the returned fields, so its hydration-specific scope is unmistakable against siblings like garmin_get_nutrition_log or garmin_get_daily_summary.

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?

Gives a concrete precondition ("Only has data if the user logs hydration in Garmin Connect") and a hard range limit, which tells the agent when results will be empty and how to bound date ranges. It does not, however, name alternative tools for related nutrition/wellness data.

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