Body Battery

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

Annotations already declare readOnly/idempotent/non-destructive, so the bar is lower, yet the description adds real context: readings are in local time, roughly six per day at named checkpoints, and events (sleep, activities, stress) are attached. It does not mention pagination or truncation behavior beyond the 92-day cap, keeping it short of a 5.

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 core purpose and row shape are front-loaded, and the routing sentence is placed before the parameter guidance. It is dense with semicolons and repeats the detail='full' behavior already in the schema, which costs a little tightness.

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 return-value burden and does so: row contents, units/scale (0-100), time zone, and the compact-vs-full distinction. Nothing an agent needs in order to call this correctly is missing.

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 the baseline is 3; the description still adds selection guidance (period preferred over dates), concrete period examples, and the 92-day limit. The detail='full' explanation largely restates the schema enum, so the added value is modest rather than substantial.

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+resource ('Daily Body Battery... over a range, one compact row per day') and enumerates the returned fields (charged, drained, highest, lowest, events, end-of-day feedback). It also names the two sibling tools it is not, so an agent can distinguish it without opening any 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: 'For today's state use get_readiness; for trends over weeks or months use summarize_wellness.' It also states the selection rule between the period enum and start_date/end_date, and the 92-day per-call cap.

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