garmin_compare_periods

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

The description adds meaningful behavioral context beyond the annotations by specifying that the tool operates on 'locally cached' data (no live fetch) and computes 'daily averages' (aggregation behavior). The annotations already cover read-only, idempotent, and non-destructive traits, so this additional cache/aggregation context earns a 4.

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 a single, front-loaded sentence with no wasted words. It efficiently communicates the core function and key constraint, earning a perfect score for 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?

Considering the moderate complexity (4 params, output schema present, strong annotations), the description is minimally adequate. It covers the purpose and a key behavioral constraint, but lacks usage guidance and parameter detail. The output schema and annotations reduce the burden, so a 3 is appropriate.

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?

With 0% schema description coverage, the description must compensate. It does clarify that there are 'two date ranges', which maps to the four parameters, but it does not explain parameter formats, inclusion/exclusion semantics, or date syntax. Param names are somewhat self-explanatory, but the description adds minimal depth beyond that.

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 uses a specific verb ('Compare') and a clear resource ('daily averages for two locally cached date ranges'), making the tool's function immediately understandable. It also distinguishes itself from sibling tools like garmin_get_day and garmin_get_trends by focusing on comparison rather than retrieval.

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?

No explicit guidance is provided on when to use this tool versus alternatives. The phrase 'locally cached' hints at a prerequisite but does not explain when comparison is appropriate or how it relates to other Garmin tools. There are no exclusions or alternative recommendations.

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