garmin_body_battery

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

With no annotations, the description carries the full behavioral burden. It does disclose the analytical enrichment (overnight charge vs daytime drain, wake-up level, deep-sleep correlation), which is genuine behavioral context, but it omits data freshness, permissions, and how the correlation is computed.

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 purpose is front-loaded in the first clause, with supporting detail following. It is short and wastes little, though much of the body is spent enumerating return values that the output schema already covers.

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?

An output schema exists, so return values need not be explained, yet the description devotes most of its length to them while omitting usage context and the `days` parameter. Adequate but with clear gaps for a metric-retrieval tool.

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?

The single `days` parameter (default 14) has 0% schema description coverage and is never mentioned in the description. Since there is one real parameter rather than zero, the baseline-4 rule does not apply and the description fails to compensate for the documentation gap.

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 names a specific resource (Body Battery) and its analytical framing (charge efficiency and drain analysis), so an agent can tell it retrieves a specific wellness metric. It does not, however, differentiate itself from adjacent metrics like garmin_recovery, garmin_sleep, or garmin_stress, which also touch overnight charging and drain concepts.

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 statement of when to reach for this tool versus alternatives, nor any prerequisites or exclusions. The agent is left to infer usage purely from the metric name among ~47 siblings.

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