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

Annotations already establish the read-only, non-destructive safety profile; the description usefully adds that data spans multiple device sources and can be stale because device data only syncs when the user opens the app, and it points to latest_date. It does not cover authorization requirements, rate limits, or how missing metrics are represented.

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 front-loaded with the returned metric set, then the intended use, then source compatibility and sync caveat. Every sentence adds operational value, with no filler.

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 read-only summary tool with no output schema, the description lists the metrics and notes period averages and latest_date, giving the agent enough to interpret the return. It remains slightly underspecified on response structure and missing-data behavior, but annotations and the simple one-parameter schema reduce the burden.

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 sole parameter (days) is fully documented in the schema with default and maximum, so the description need not restate it. The description's mention of period averages is contextual but does not add syntax or constraints beyond the schema.

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 names a specific resource (daily health from the user's watch) and enumerates the metrics it returns, so the agent knows exactly what the tool produces. It stops short of differentiating from siblings such as get_cardio_summary or get_workout_stats, which also cover fitness/activity data.

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?

It gives a clear use case (recovery, readiness and fitness questions) and a freshness precondition. It does not name when to prefer it over sibling summary/stat tools, so routing among overlapping health and workout tools remains partly ambiguous.

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