Get body battery

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

Goes well beyond the annotations: it discloses the request-cost model ('One Garmin request whatever the range, so keep it to days') and the output fidelity contract ('Garmin's JSON as it comes: field names are Garmin's and nothing is converted'). Annotations only say readOnly/idempotent/openWorld; the cost and raw-payload behavior is genuinely additive.

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?

Purpose is front-loaded in the first sentence, then routing guidance, then cost, then payload shape. Every sentence carries distinct information and none repeats the name or title.

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 structure need not be re-explained, yet the description still flags the practically important fact that fields are raw/unconverted Garmin names. Combined with the request-cost note and the sibling routing, an agent has everything needed to call this correctly.

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%, and the schema already documents start and end including end's default-to-single-day behavior, so the schema does the heavy lifting. The description only gestures at the range ('each day from start to end') without adding format or boundary semantics, 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?

States a specific verb and resource ('Return Garmin's own body battery record for each day from start to end') plus a distinguishing modifier ('unprocessed'), which separates it from the aggregation siblings it explicitly names. An agent can tell it apart from get_day_summary and get_trend without opening either schema.

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 explicit routing rules with named alternatives and the conditions that select them: get_day_summary for one day's high/low, get_trend with metric body_battery for daily highs over weeks or months. It also states when to use this tool itself (the detail behind a day's number).

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