health_daily_brief

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 adds meaningful behavioral context beyond that: the tool returns a baseline comparison and defaults to today. This is genuine added context rather than a repeat of annotations.

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 sentences with zero filler. The core capability is front-loaded, the baseline-comparison behavior is stated compactly, and the usage guidance follows naturally. Every sentence earns its place.

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?

For a single-parameter read-only tool with an output schema, the description covers the main behavioral details: what data is returned, how it is compared, the default date, and when to use it. It omits the exact date string format, but the output schema and type annotation make the tool safely callable. Complete enough for its complexity.

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 0%, so the description carries the burden of explaining the single 'date' parameter. It does add value by stating 'Defaults to today' and implying the parameter selects the day, but it does not specify the accepted date format. This is partial compensation, not full coverage, so a 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?

The description opens with 'One-call snapshot of a single day' and enumerates the specific metrics included (sleep, resting HR, HRV, etc.), making the resource and action unambiguous. It also adds the distinguishing trait 'each compared against your own trailing baseline'. However, it does not explicitly differentiate itself from the sibling health_daily, so it falls just 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?

The description provides clear usage context: 'This is the right first call for "how am I doing today"' and 'Defaults to today'. This tells the agent when to prefer this tool, but it does not name alternatives or state when not to use it, so it lacks the explicit when/when-not structure of a 5.

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