garmin_fitness_age

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

No annotations are provided, so the description carries the full behavioral burden. It adds useful interpretation of the widening/narrowing gap and states the aggregation period, but it does not disclose read-only safety, data availability, time-range constraints, or other operational behavior.

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 description is front-loaded, compact, and every sentence adds value. It defines the metric, the aggregation, and the interpretation without unnecessary text.

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?

The tool is simple with one optional parameter and an output schema, so the description does not need to explain return values. It covers the metric meaning, aggregation options, and interpretation, though it omits when to prefer this tool over adjacent fitness metrics.

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 0%, so the description must compensate for the single period parameter. It does so by stating that results can be aggregated by week or month, though it does not mention the schema default of month.

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 states a specific verb and metric: it shows fitness age vs chronological age trajectory, aggregated by week or month. It clearly identifies the resource, but it does not explicitly distinguish this tool from sibling Garmin metric tools such as garmin_vo2max or garmin_training_status.

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 explains how to interpret the metric, which implies it is a query tool, but it does not say when to use this tool versus garmin_vo2max, garmin_training_status, or other fitness-related siblings. There are no explicit when-to-use or when-not-to-use guidelines.

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