Get nutrition / food log (one day)

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

Annotations already declare readOnly, idempotent, and non-destructive, so the safety profile is covered. The description adds genuinely useful behavioral context beyond that: the data-completeness caveat about the user needing to log food, plus the scope of returned content, which helps the agent decide whether a null-ish result is an error or expected.

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?

A single front-loaded sentence with the resource and scope first, followed by the enumerated payload and one caveat sentence. The parenthetical field list ('protein, carbs, fat, fiber…') and meal enumeration are slightly dense but each element conveys real payload information, so nothing is wasted.

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 describing return values, and it does so by naming the major payload sections an agent would act on. It stops short of explaining response shape or how mealDetails/meal IDs relate, but for a read-only single-day fetch this is close to sufficient.

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 100%, so every parameter (date format, mealId, the three include* toggles and their defaults) is already fully documented in the schema. The description only loosely gestures at parameters by mentioning goals and meal details; it adds no syntax or usage nuance beyond the schema, so the 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?

Opens with a specific verb and resource ('Get the user's food log for one day') and then enumerates exactly what is returned: goals, nutrient totals, logged foods with serving sizes, and meal-by-meal breakdown. No sibling tool in the set covers nutrition, so the scope is unambiguously distinct from the sleep, steps, hydration, and weight tools.

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 gives clear operating context, including the key precondition that data only exists if the user logs food in Garmin Connect, which tells the agent how to interpret an empty response. It does not explicitly route the agent away from alternatives (e.g., whether the daily summary also carries nutrition), but no real competing sibling exists here.

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