Get Health Metrics

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

Annotations already include readOnlyHint=true and openWorldHint=true, so the description needs only to add context beyond those. It adds that metrics include heart rate and step count, but does not disclose any additional behavior like aggregation logic, latency, or limitations. This is adequate for a simple read operation but not enriching.

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 description is a single, clear sentence that front-loads the action and resource. It contains no filler and gets straight to the point.

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 tool with one optional parameter, no output schema, and a read-only annotation, the description is sufficient. It specifies the returned data type (health metrics) and key examples (heart rate, step count). The lack of an exhaustive list of metrics is acceptable given the simplicity.

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 input schema fully describes the date parameter (format, default), so schema coverage is 100%. The tool description adds minimal extra meaning beyond implying that the metrics are for a specific date. The schema does the heavy lifting, so a baseline score of 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 clearly states the tool retrieves daily health metrics (heart rate, step count) for a specific date. It uses a specific verb ('Get') and resource ('health metrics'), distinguishing it from more granular siblings like get_steps or get_heart_rate.

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 no guidance on when to use this tool versus the many sibling tools that cover individual metrics (e.g., get_steps, get_heart_rate). It does not mention that this is an aggregate option, nor does it exclude cases where more specific tools would be preferable.

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