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

Annotations already declare readOnlyHint=true and openWorldHint=true, so the safety profile is covered. The description then adds genuine behavioral value by disclosing the return shape and, importantly, that the result is a merge of two distinct series (metricId 22 active and metricId 23 resting/BMR) — something the annotations and schema do not convey.

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?

Two tightly written sentences with the core purpose front-loaded and the return contract second. No filler, and every clause carries information the caller needs.

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 present, the description compensates by specifying the exact returned structure `[{calendarDate, active, resting, total}]`. For a simple two-parameter read tool, an agent has everything needed to call and interpret it.

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 100% and both date parameters are fully documented in the schema (format and UTC semantics). The description only restates 'over a date range' without adding format, timezone, or boundary-inclusion detail, so baseline 3 is appropriate.

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 resource (calories per day) with precise scope (active, resting, and total, over a date range), so an agent knows exactly what it retrieves. It does not explicitly differentiate itself from overlapping siblings like get_daily_stats or get_stats_and_body, which also surface daily calorie-adjacent data, so it stops short of a 5.

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 explicit when-to-use, when-not-to-use, or named alternative. Usage is only implied by the tool name and the 'over a date range' phrase; with many daily-stats siblings available, the agent gets no help routing among them.

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